It's enough to buy a gift for grandma with filial piety. In fact, grandma doesn't care what you buy. As long as you think about her and miss her, she will be satisfied. So I'll give you some small suggestions, you can choose.
1. 100 yuan is enough to buy a big cake for grandma. Go to the cake shop and order a flavor that grandma likes. Ask the person who makes the cake to write blessings such as "May you be as blessed as the East Sea and live forever", or write "Grandma, I love you". Grandma will be happy!
2. You can go to the local TV station to order an old song for grandma, or a clip of Peking Opera or Lv Opera that grandma likes. When the time comes, the whole family will watch it with grandma, and they will have a lot of fun.
3. Customize a crystal piano music box with a family photo or make a batch of real dolls in the shape of the whole family. It is very beautiful. Put it on the table. When everyone goes to work or school, grandma can often see the family and won't be lonely.