You must be very sad when he tells you in your dream that he is very sad. Judging from Freud's dream interpretation, it just shows that you miss grandpa very much. Crying may be the reappearance of the scene a month ago. In my dream, I would rather not have myself, so I turned your crying into grandpa's crying, and as a result, you were very sad.
However, everyone will be influenced by traditional culture. I suggest you worship God and burn paper money. This is a respect for the deceased and a comfort to one's own soul.