Al final del día, mi hija dice que merece la pena madrugar si puede volver a la granja y ayudar a la granjera.

Yes, literally al final del día means at the end of the day.

In modern Spanish, it can also be used idiomatically like English when all is said and done / ultimately. So in this sentence it may sound either:

• literal: at the end of the day
• idiomatic: all things considered / in the end

A small usage note: some speakers feel the idiomatic use is influenced by English. In more traditional Spanish, you might also hear:

• al fin y al cabo
• a fin de cuentas

But al final del día is still very understandable and common.

Because de + el contracts to del in Spanish.

So:

• de + el → del
• a + el → al

That is why you get:

• Al final del día

from:

• a el final de el día

But in correct Spanish, those contractions are normally required, so you say al and del, not a el or de el.

Because Al final del día is an introductory phrase placed before the main clause.

Spanish often uses a comma after this kind of opening expression, especially when it sets the scene or gives a general framing idea:

• Al final del día, mi hija dice...

It is similar to English punctuation in:

• At the end of the day, my daughter says...

The comma helps separate the introductory phrase from the main statement.

Because decir que is the normal way to report what someone says when it is followed by a full clause.

Here:

• mi hija dice que merece la pena madrugar

literally means:

• my daughter says that getting up early is worth it

The word que introduces the reported statement, just like that in English.

Compare:

• Mi hija dice que viene mañana. = My daughter says that she’s coming tomorrow.
• Mi hija dice la verdad. = My daughter tells the truth.

So decir que is a very common structure.

Merece la pena means it is worth it / it is worthwhile.

Literally, it is something like:

• it deserves the trouble / effort

But in real usage, it simply means something is worth doing.

Examples:

• Merece la pena intentarlo. = It’s worth trying.
• No merece la pena discutir. = It’s not worth arguing.

In your sentence:

• merece la pena madrugar

means:

• getting up early is worth it

This is a very common expression in Spanish.

Both are possible, but merece la pena + infinitive is the more natural and common pattern.

So Spanish often says:

• Merece la pena madrugar.
• Merece la pena estudiar.
• No merece la pena preocuparse.

This structure is similar to English it’s worth getting up early, where the action comes after the expression.

You can also say:

• Madrugar merece la pena

but that feels more emphatic or stylistically marked, because madrugar is being placed first as the topic.

Madrugar means to get up very early or to wake up very early, usually earlier than one would like or earlier than normal.

It is stronger than just:

• levantarse temprano = to get up early

Madrugar often suggests an early start, such as for work, travel, or chores.

So:

• merece la pena madrugar

is more like:

• it’s worth getting up really early
• it’s worth making an early start

Because after si meaning if, Spanish normally uses the indicative, not the present subjunctive, when talking about a real or possible condition.

So:

• si puede volver... = if she can go back...

is correct.

You would not normally say:

• si pueda volver...

in this kind of sentence.

Very generally:

• si + present indicative for real/possible conditions
  
  • Si puede, vuelve.
• si + imperfect subjunctive for unlikely/hypothetical conditions
  
  • Si pudiera, volvería. = If she could, she would go back.

It refers to mi hija.

The sentence is:

• mi hija dice que merece la pena madrugar si puede volver a la granja...

So the understood subject of puede, volver, and ayudar is the same person: my daughter.

Spanish often leaves subjects unstated when they are clear from the context. So instead of repeating ella, Spanish simply uses the verb form:

• puede = she can
• volver = to return
• ayudar = to help

Because Spanish regularly drops subject pronouns when the subject is already clear.

So instead of:

• mi hija dice que merece la pena madrugar si ella puede volver...

Spanish naturally prefers:

• mi hija dice que merece la pena madrugar si puede volver...

The verb ending and the context already tell you who the subject is.

Including ella is possible, but it would usually add emphasis or contrast, for example:

• ...si ella puede volver, pero su hermano no.

Volver means to return / to go back.

When you say where someone returns to, Spanish uses a:

• volver a casa = to go back home
• volver al trabajo = to return to work
• volver a la granja = to go back to the farm

So here a is just the normal preposition after volver when naming the destination.

They are different words:

• la granja = the farm
• la granjera = the female farmer / the farmwoman

They are related in form, but one is a place and the other is a person.

Compare:

• granja = farm
• granjero = male farmer
• granjera = female farmer

So in the sentence:

• volver a la granja = go back to the farm
• ayudar a la granjera = help the female farmer

Because ayudar normally takes a before the person being helped.

So Spanish says:

• ayudar a alguien = to help someone

Examples:

• Ayudo a mi madre.
• Ayudamos al profesor.
• Quiere ayudar a la granjera.

This is related to the personal a, although with ayudar it is especially standard and expected.

So:

• ayudar a la granjera

is the normal way to say:

• to help the female farmer

Yes, you could, but the nuance changes slightly.

• madrugar = to get up very early / make an early start
• levantarse temprano = to get up early

Madrugar is more compact and often more expressive. It can suggest effort or sacrifice.
Levantarse temprano is more neutral and descriptive.

So:

• merece la pena madrugar

sounds very natural if the idea is that the early start is hard but worth it.

Because they depend on other verbs and structures in the sentence.

Breakdown:

• puede volver = she can return
• [puede] ayudar = [she can] help

After poder, Spanish uses an infinitive:

• puede volver
• puede ayudar

Also, after merece la pena, Spanish often uses an infinitive to name the action that is worth doing:

• merece la pena madrugar

So the sentence contains several infinitives because Spanish uses them very naturally after verbs like poder and expressions like merecer la pena.

It is a coordination of two actions linked by y:

• volver a la granja
• ayudar a la granjera

The natural reading is that both actions are part of the reason why getting up early is worth it. In other words, it is worth getting up early if she can:

1. go back to the farm, and
2. help the female farmer

Since both infinitives depend on puede, Spanish does not need to repeat the verb:

• si puede volver a la granja y ayudar a la granjera

This is equivalent to:

• si puede volver a la granja y puede ayudar a la granjera

but without the unnecessary repetition.

Yes, that is the most natural interpretation.

• mi hija dice que... = my daughter says that...

The present tense can report:

• something she says regularly
• her current opinion
• a general repeated statement

It does not have to mean she is saying it right now at this exact moment.

If you wanted a one-time past report, you might say:

• mi hija dijo que... = my daughter said that...

So the present here suggests an ongoing or current viewpoint.