titi ha sigoto ga owattara, sugu ie ni modotte kimasu.

They are marking different things.

• 父は sets father as the topic: As for my father...
• 仕事が終わったら has its own smaller clause, and inside that clause 仕事 is the thing that ends / is finished, so it gets が.

So the structure is roughly:

• 父は = as for my father
• 仕事が終わったら = when work is finished
• すぐ家に戻ってきます = he comes back home right away

It is very common in Japanese to have は in the main sentence and が inside a subordinate clause.

終わったら is:

• 終わる = to end, to be finished
• 終わった = ended / finished
• 終わったら = when it has ended, after it ends, or if/when it ends

In this sentence, it means:

• when work is finished
• after work ends

Even though 終わった looks past, ～たら is often used for a future condition:

• 仕事が終わったら、帰ります。
  When work is over, I’ll go home.

So here it is not talking about the past; it is talking about what happens once that condition is met.

Because 終わる is an intransitive verb.

• 終わる = something ends / is finished
• 終える = to finish something

So:

• 仕事が終わる = work ends / work is finished
• 仕事を終える = to finish work

That means:

• 仕事が終わったら = when work is finished
• 仕事を終えたら = when he finishes work

Both can work in many situations, but they are slightly different in viewpoint:

• 仕事が終わったら focuses on work being over
• 仕事を終えたら focuses on someone completing the work

The sentence you have uses the more neutral, very common 仕事が終わったら.

戻ってきます adds the nuance of coming back toward the speaker’s side or home base.

• 戻る = to return
• 戻ってくる = to come back

So:

• 家に戻ります = returns home
• 家に戻ってきます = comes back home

In English, both may simply be translated as returns home, but Japanese often cares about viewpoint.

Here, くる suggests movement toward the place that matters to the speaker, which is very natural with home.

に marks the destination.

• 家に戻る = return to home

With movement verbs, に often marks the place someone goes to.

You may also see へ with directions, but に is very natural here because it marks the actual destination clearly.

• 家に帰る
• 家へ帰る

Both are possible, but に is especially common when the endpoint matters.

すぐ is an adverb meaning right away, immediately, or soon.

In this sentence:

• 仕事が終わったら、すぐ家に戻ってきます。

it modifies the action of returning home.

Japanese adverbs are fairly flexible in position, as long as they come before what they modify. So these are all natural:

• 仕事が終わったら、すぐ家に戻ってきます。
• 仕事が終わったら、家にすぐ戻ってきます。

The first one is probably the most natural and easiest for learners.

Yes, 父 here normally means my father.

Japanese often omits things that are understood from context. When talking about family members, it is very common not to say 私の if it is obvious.

So:

• 父 = my father
• 母 = my mother

Also, 父 is the usual word for your own father when speaking to someone else. By contrast:

• お父さん is often used when addressing your father directly, or when referring to someone else’s father more politely.

So in a sentence like this, 父 is exactly what you would expect.

Because Japanese often changes family terms depending on whose family member you mean and who you are talking to.

For your own father, when speaking to others, the standard word is:

• 父

For someone else’s father, or when speaking directly to your own father, you often use:

• お父さん

Examples:

• 父は会社員です。 = My father is an office worker.
• お父さんはお元気ですか。 = Is your father doing well?
• お父さん、ちょっと聞いて。 = Dad, listen a second.

So 父 is the natural choice here.

Because politeness in Japanese is mainly shown in the predicate, not in every word.

Here, the politeness comes from:

• きます rather than くる

So the sentence is polite overall because the verb is in ます-form.

Using 父 does not make the sentence rude. It is simply the normal noun for my father in this context.

Japanese often mixes:

• plain-style nouns and vocabulary
• polite verb endings

That is completely normal.

It is non-past.

Japanese does not divide this form into present vs. future the same way English does. きます can mean:

• comes
• will come

In this sentence, because of the context when work is finished, it is understood as either:

• a future action: he will come home right away
• or a habitual action: he comes home right away whenever work ends

So the exact English tense depends on the situation, but the Japanese form is simply non-past.

Yes.

Japanese non-past forms often allow both interpretations:

• one future event
• habitual/repeated action

So 父は仕事が終わったら、すぐ家に戻ってきます。 can mean:

• My father will come home right away when work is over.
• My father comes home right away after work.

You decide from context which one is meant.

The comma helps separate the conditional/time clause from the main clause:

• 仕事が終わったら、 = when work is finished,
• すぐ家に戻ってきます。 = he comes back home right away.

It makes the sentence easier to read, especially because ～たら creates a natural pause.

Japanese punctuation is more flexible than English punctuation, so the comma is helpful but not always absolutely required.

Yes, in many situations 帰ってきます would sound very natural too.

• 帰る / 帰ってくる often means go home / come home
• 戻る / 戻ってくる means return / come back

So:

• 家に帰ってきます = comes home
• 家に戻ってきます = comes back home / returns home

帰る is often the more basic everyday verb for going home.
戻る can sound a little more like returning to a previous place/state.

In this sentence, 戻ってきます is perfectly fine and natural, but 帰ってきます would also be common.

Because Japanese often omits things that are obvious from context.

Once the sentence starts with 父は, the listener already knows who the sentence is about. So Japanese does not need to repeat he.

English often requires repeated subjects:

• My father, when work is over, he comes home right away.

But Japanese usually does not:

• 父は仕事が終わったら、すぐ家に戻ってきます。

The topic 父は carries through the sentence unless something changes.