My sister-in-law went to Charlie's school
Had to think on this for a bit so hope it is right
The farmer told the students they were welcome to come back at anytime!
1. The adverb that modifies the verb is c) ever. Without it, it wouldn't be completely clear as to which time frame the speaker refers to. It may have been for example the last year, or in some other particular moment.
2. The adverb that modifies the verb is b) always. It adds to the sense of urgency of wearing a life jacket when rafting. Without it, the meaning of this sentence wouldn't be so precise.
He went to buy some groceries.
The rabbit hopped around the field.
You and me are friends.
Mom went to the mall.
Hope I help,
~Taco.