Greetings,
I do hope we get some others involved here, but again, perhaps I can get this started.
When you cross over, you will understand so much more than our human perspective allows. When you and your mother part finally, it will be by mutual agreement so it won't come as surprise to you. That aspect of her will probably fade or rest when no one from that lifetime is seeking her.
Since your mother said your grandfather is your connection now, I'm guessing she had prior committments. You and he have had some prior lives together, I expect, or else he wouldn't have been chosen for your helper now. Why distract her from her involvements when she has hinted that you have others to look to?
These assignments are group decisions, not just the people you are aware of, so his death in the 1960's is somewhat immaterial. He must care alot to keep having you in his lives! It sounds like he is waiting for you (at least until you find you've been assigned a new helper) so he knows you well. You can ask him anything you would ask your mother and his answers will let you know how to continue your questions. When you meet him there, you may recognize him from another time and place, not like old Gramps at all!
You can use the imagination method Bruce suggests and save yourself the psychic's fees. That way you get your information direct, fully laden with the emotional overtones that are meant for you, with no warpage from some medium view. Have you read that part yet, about having a calm uninterrupted time and place? Just address your grandfather (mentally, not necessarily out loud.) When I want to contact someone that way I usually announce a couple of times in the day before, "I intend to find --- and speak with them tomorrow /soon."
Being your mother was a big position so you and she have probably worked up to that with various other relationships in the past, so i can see that your loss of her is a big one. But so many family members up there love you! I hope you will get to know them by contacting your grandfather soon.
Love, bets