advice please

My grandma died about seven months ago and my grandpa wants more than anything to be with her. He has been sick for a long time and has almost died twice but hasn't. My mom and I thinks that he is holding on because he doesn't want to hurt us. We don't want him to leave yet but we don't want him to suffer. I need help on deciding on weather or not we should tell him that we will be ok if he lets go.