Answer
756 possible family nights
Explanation
There are 9 family members ( = 2 adults + 7 children)
Given that each family member is allowed 3 meal suggestions, then there are 9x3 = 27 meal suggestions.
Given that each child is allowed 4 activity suggestions, then there are 4x7 = 28 activity suggestions.
Each family night consists of 1 meal and 1 activity. Therefore, there are 27x28 = 756 possible family nights