Antes de que se haga de noche, quiero volver a casa.

Because antes de que is used before a conjugated verb:

• Antes de que se haga de noche = before it gets dark

By contrast, antes de is used before a noun or an infinitive:

• antes de la cena = before dinner
• antes de salir = before leaving

So in your sentence, since se haga is a full verb form, de que is needed.

Because antes de que normally triggers the subjunctive when the action is still in the future or has not happened yet from the speaker’s point of view.

Here, getting dark is something expected to happen later, so Spanish uses the subjunctive:

• Antes de que se haga de noche...

Not:

• Antes de que se hace de noche ❌

This is a very common pattern:

• antes de que llegues = before you arrive
• antes de que empiece = before it starts
• antes de que anochezca = before night falls

Also, haga is the present subjunctive of hacer, which is irregular:

• yo haga
• tú hagas
• él/ella haga

It means it gets dark or night falls.

Literally, hacerse de noche is something like to become night, but in natural English we say:

• to get dark
• for night to fall

This is a fixed Spanish expression. Similar ones are:

• se hace tarde = it’s getting late
• se hizo de día = it became daytime / dawn came

So antes de que se haga de noche is a very natural way to say before it gets dark.

In hacerse de noche, the se is part of the expression hacerse. It is not really reflexive in the everyday English sense of doing something to oneself.

You should learn hacerse de noche as a chunk:

• se hace de noche
• se hizo de noche
• cuando se haga de noche

Spanish often uses se in verbs that describe a change of state:

• hacerse tarde = to get late
• hacerse viejo = to grow old
• hacerse de día = to become daytime

So here, the best approach is to remember the whole phrase, not to try to translate se word by word.

Yes. Those are possible alternatives.

For example:

• Quiero volver a casa antes de anochecer.
• Quiero volver a casa antes de que se haga de noche.

Both mean roughly the same thing.

A few notes:

• anochecer is a single verb meaning to get dark / night to fall
• hacerse de noche is a very common everyday expression
• antes de hacerse de noche may also be heard, though antes de que se haga de noche and antes de anochecer are more clearly standard and common

So the sentence you were given is perfectly natural, but it is not the only possible way to express the idea.

Because volver means to return / to go back, and Spanish uses a to mark the destination:

• volver a casa = to go back home
• volver al trabajo = to go back to work
• volver a Madrid = to return to Madrid

So a here is just the normal preposition used with movement toward a place.

Because casa without an article often means home in a general, personal sense.

So:

• volver a casa = to go back home
• llegar a casa = to arrive home
• estar en casa = to be at home

But la casa usually refers more specifically to the house/building:

• Volví a la casa de mis abuelos = I went back to my grandparents’ house

So in your sentence, a casa is used because the meaning is simply home.

Yes, absolutely.

Both are correct:

• Antes de que se haga de noche, quiero volver a casa.
• Quiero volver a casa antes de que se haga de noche.

The difference is mostly about focus and style:

• starting with Antes de que se haga de noche emphasizes the time limit
• putting it at the end sounds slightly more neutral and straightforward

In everyday conversation, the second order is probably a bit more common, but both are perfectly natural.

Yes, when the sentence starts with a subordinate clause like this, the comma is standard:

• Antes de que se haga de noche, quiero volver a casa.

If the same clause comes after the main clause, you normally do not use a comma:

• Quiero volver a casa antes de que se haga de noche.

So the comma here is there because the before-clause comes first.

Because quiero volver expresses a wish/intention:

• quiero volver = I want to go back

It focuses on what the speaker wants.

A future form would mean something slightly different:

• volveré a casa antes de que se haga de noche = I will return home before it gets dark

That sounds more definite or like a promise/plan.
So quiero volver is about desire; volveré is about a future action.

Almost. In this sentence, both work:

• Quiero volver a casa
• Quiero regresar a casa

They both mean I want to go back home.

However, in Spain, volver is generally more common and everyday. Regresar is correct, but it can sound a little more formal depending on the context.

So volver a casa is the most natural choice for many speakers in Spain.