The Double Ninth Festival is a festival for the elderly. Since ancient times, there has been a custom of climbing high to worship ancestors. Since it is a festival, of course you have to go back to visit the elderly. When parents are not around, it is a heavy responsibility. Here are a few ideas for you:
First, you can accompany the old man to do something he wants to do but cannot do, such as going on an outing to a distant place. Of course, the weather must allow. You can also accompany him to play chess or something, which will make him very happy.
Second, you can take grandpa to see a play. The elderly will like opera very much. Go to the scene to watch a show. I think he will be very excited. Such a festival must be good.
Third, bring some gifts. You can bring some delicious food, or a pot of flowers and plants, or a painting. Grandpa who is enjoying his old age will like it very much. You can also choose a real doll and make a family portrait for him. Put it at home. Even if his parents are not around, he will feel that he has many children and grandchildren. It is very good.