To see your grandfather in your dream symbolises tradition, protection, wisdom, and a caring nature. Consider the qualities and characteristics that exist in your own grandfather. 

If your grandfather is dead and you dream that he is alive, then it may just mean that you miss them and are trying to relive the time you spent with them when he was alive. If you dream that your grandfather is doing odd things, then it implies that you are still trying to understand his death. Perhaps you haven’t come to terms with why he passed away. Dreaming that your dead grandfather is mocking you points to your difficulty in connecting with him. You feel that he is somehow disappointed in you and in the decisions you made.