Responses
The grandfather we have seen is her maternal grandfather (her mothers father). The fief belongs to her father's family, and since the grave is in the fief we can assume it belongs to her paternal grandfather. We haven't been told anything about her paternal grandfather, so it's either unimportant or it will come at another time.
So that grandfather was from her fathers side not from her mother side..
When did her grandfather died and why?