Susan – Obviously you have the ability to communicate with your grandparents. But the first dreams were very clearly an indication of someone going. So I feel there is a shift in your communications as they are not directly about death, but more like visits.
The business about your mother and arguing with her is though, a borderline situation. So I suggest you ask for a dream to clarify this. Because your mother has such a deeper connection with you, it might be more difficult for you to get a clear dream if it does indicate her death. But asking for clarity could cut through the difficulty.
Hopefully the fact that you have such clear indications that death is not the end will make it easier. Though, as I say, it may be just a visit.
Tony