Hindi ko pa nasasagot ang email niya dahil wala pang internet sa bahay.

Because ako and ko are different case forms of I in Filipino.

• ako is the ang-form pronoun.
• ko is the ng-form pronoun.

In this sentence, the verb pattern makes ang email niya the ang-marked focus/topic, so the doer I appears as ko:

• Hindi ko pa nasasagot ang email niya.

A very rough way to think about it is:

• ang email niya = the thing being talked about as the main item
• ko = the person doing the action to it

So ko is the correct form here.

In standard Tagalog, short pronouns like ko, mo, niya usually come before particles like pa, na, din/rin when they cluster after the first word.

So the normal order is:

• Hindi ko pa nasasagot...

not usually:

• Hindi pa ko nasasagot...

A useful beginner rule is:

• pronoun first
• then particles like pa

So:

• Hindi ko pa alam.
• Hindi niya pa sinabi.
• Hindi namin pa would be wrong; it should be Hindi pa namin only if namin is not in the same clitic position pattern, but for short enclitic pronouns like ko, the usual safe model is Hindi ko pa...

For this sentence, Hindi ko pa... is the form to remember.

Pa usually means still or yet, depending on whether the sentence is positive or negative.

In this sentence it appears in two places:

1. Hindi ko pa nasasagot...
   = I haven’t answered it yet / I still haven’t managed to answer it

2. wala pang internet...
   = there is still no internet yet

So the two pa's are not redundant. They modify different parts of the sentence:

• the first pa goes with not answering yet
• the second pa goes with the internet still not being available

Also, pang in wala pang internet is just pa plus the linker -ng before the next word.

Nasasagot comes from the root sagot, meaning answer.

This form can be tricky, but in this sentence it suggests something like:

• haven’t managed to answer yet
• still can’t answer yet
• have not gotten to answer yet

Because the next clause says dahil wala pang internet sa bahay, the sentence clearly suggests that the speaker is being prevented by circumstances.

A helpful comparison:

• sinagot ko ang email = I answered the email
• nasagot ko ang email = I managed to answer the email / I was able to answer the email
• hindi ko pa nasasagot ang email = I still haven’t managed to answer the email

So nasasagot here carries a slight sense of ability or successful completion being blocked.

Here ang is marking the noun phrase that the sentence is organized around: ang email niya.

So:

• ang email niya = the email being answered
• ko = the one doing the answering

This is part of the Filipino focus system. Ang is not just the same as English the, even though it may sometimes look that way in translation.

In this sentence, ang email niya is the item in focus, so ang is used.

It can mean either.

Filipino third-person singular pronouns do not show gender the way English does. So:

• niya = his, her, or sometimes their in certain real-life contexts, depending on context

In this sentence, email niya simply means:

• his/her email

You need context to know which one.

Literally, it means:

• there is still no internet yet

Wala is used for absence or nonexistence. It often works like there is no... / there isn’t any...

So:

• May internet. = There is internet.
• Walang internet. = There is no internet.
• Wala pang internet. = There is still no internet yet.

This is a very natural Filipino way to express that something is not available.

Yes, you could say kasi instead.

Both mean because, but there is a small difference in tone:

• dahil = neutral, standard, a bit more formal
• kasi = very common in everyday speech, more conversational

So these are both natural:

• Hindi ko pa nasasagot ang email niya dahil wala pang internet sa bahay.
• Hindi ko pa nasasagot ang email niya kasi wala pang internet sa bahay.

If you want a slightly more neutral or written feel, dahil is a good choice.

Because sa bahay can already mean at home / at the house, and the context makes it clear whose home is meant.

In this sentence, the speaker is talking about why they cannot answer the email, so sa bahay is naturally understood as at my house / at home.

You could make it more explicit if needed:

• sa bahay ko = at my house
• sa bahay namin = at our house

But plain sa bahay is very common and natural when the owner is obvious from context.

Yes. Email is a loanword, but it behaves like a regular noun in Filipino and can take normal markers:

• ang email
• ng email
• sa email

So in your sentence:

• ang email niya = his/her email

This is completely natural. Filipino freely uses many English loanwords this way, especially for technology and modern life.

Yes. Filipino word order is flexible, so you can move the reason clause to the front:

• Dahil wala pang internet sa bahay, hindi ko pa nasasagot ang email niya.

That means essentially the same thing.

The original version is also very natural:

• Hindi ko pa nasasagot ang email niya dahil wala pang internet sa bahay.

So the choice is mostly about emphasis:

• original order: first states the problem, then gives the reason
• reordered version: first gives the reason, then states the problem