In response to the question "What does she do after school?", which is right? She does her homework/She is doing her homework.
She does her homework
If the question is asking about something in general, for instance:
What does she do after school?
The answer would be:
She does her homework. - so here we're saying that, in general, every day after school she does her homework.
We could use the answer She is doing her homework to a question asking what she is doing right now.