X.O.
For me it depends on her health & personality. My grandma is a VERY hearty 90 year old and we had a huge bash for her 2 months ago (at a country club, so no one had to be the official host/ess). All her great-grandchildren were there (LOTS of little kids). My aunt hired a professional photographer for the evening, so we were able to get some great candids and family pictures together. We did a roast, where we all had the chance to tell humorous stories about her--she's QUITE the character :)
What is your mom's tolerance level for noise?
Does she see her grandkids often?
Is she in good health?
Will the kids be very upset if not included?