Answer:
The answer option if the 2nd one. Garza and Smith's Hardware Store is my aunt's favorite store.
Step-by-step explanation:
Since we are referring to 2 people Garza and Smith's Hardware Store is legit. For example if we say that Luke's and Sam's dog, it wouldn't be correct because with put 2 ('s) in the sentence. It is also not grammatically correct. Therefore it is the 2nd one.
Hope this helped! :)