Fill in the blank with a suitable option:
"My mother was so helpful while she was staying with us"
"What ____________ to do?"
The Past tense is used to refer to a completed action in the past but with a clear reference to the specific time of action in the past.
Here in the question, the first person is saying that her mother was helpful while she was staying with them (while here suggests past tense), & the second person is asking what all things she (mother) helped him/her doing. As the reference is being made to an action that happened in the past with reference to specific time period ("while she was staying with us"), therefore the correct tense to use here is Simple Past Tense.
Here the sentence is the question form.
A sentence of Simple Past Tense in question form is formulated as: did + [subject] + [root form of the verb]Here the verb is help (root form of the verb).
Therefore the correct formulation here is : did + she + help