Guess I don't get it. Make the quilt, get what you would normally buy to make the item. Shouldn't make any difference who your giving it to. If was going to a friend would you be worried about the extra yd.??? Be happy you can do a little something for "Grandma" As for your MIL first of all does she drive?? If so just invite her over for Sunday dinner at least once a month, Hubby should go over there at least a couple times a month anyway just to make sure she's ok. She is LONELY. She just wants to be a part of the family.
I lost both my parents with in 3 months. I wish she could come for dinner.