Question

My son ..... (Do) his homework while his mother ......(take) the lunch. Fill in the blank with correct form of verb.

Answer 1

does..... and..... taken

Answer 2

Did .........    was taking

It talks about 2 actions: doing homework and having lunch.

Homework was done while 'eating action was ongoing'

Hence the on going action in 'past continuous' and 2nd action in simple past.