A.
I got this idea from a teacher who appreciated the gift she got once - a gift card to a movie rental place (whatever is nearby) tied to a bag of microwave popcorn. This can be a very inexpensive gift - just $5 on the card and one bag of popcorn - perfect for a movie night at home. Or you can spend a little more - $20 on the card and a whole box of popcorn. Maybe even add some hot chocolate. Tie it with some pretty ribbon and it even looks fun!
I think consumable things (gift cards, food) are great gifts for teachers who get a lot of little knick-knacks. And you don't have to feel cheap if you only put $5 on the card, because that's enough for one movie rental.