My mom buried both moms on her birthday, different years,
I almost got rattlesnake bit on mine.
Since my wife left I don't celebrate anything, no Christmas, Thanksgiving, Easter, Memorial day, 4th of July & no B-days.
Some people feel more lonely during Celebration and miss the joy of the time....
For some of us we feel all days are alike, so the loneliness is deeper not related to times...
For me to participate in any of these, doubles my pain, first I am already an Outlier, there is the pain for that, I can't participate on a level that is worth the effort, and I have no one to share a celebration with that matters and after all you really can't celebrate by yourself, you can think on it, but to feel it it has to be shared, so I just shut my lights off on Halloween and wait till after for good prices on candy, same with Valentines and Easter for chocolate, wait till after Christmas to do shopping for good deals, after Thanksgiving for good deals on food, after all I am an Outlier. I don't operate at societies frequency.
If she just dropped out of the event, Grad moms are getting older, things get harder and take more of what you got to get out and do it, even the stress of a B-day, when you get older it gets harder. and there comes a time when you have to say no, even though you don't want to. And a grand-mom NT'er, may be getting to old for the excitement of an Aspie party.
If times, with in times, really matters, you have to find another to share it with, your grand-mom wont be here for ever...
Spend the week walking around your area, go into obscure stores, for no reason than it looks like you need to go there, get on a city bus if you got one some are free, ride it downtown use caution if your in LA or Chicago go during the mornings the lower world sleeps then.
Don't sit at home and waste it on video games,
Make it a good Quest to find new things & Journey to find another lost soul in middle earth, bring back a talisman each day of your B-day Vacation week, like a "roundabout" your talismans quests will lead you through your journey to find the lost soul, because your ASD this will be easier you may find them on the first day but you will still have to quest the talismans to prove the lost soul...
Walk or Bicycle, try not to drive much, just to a park and ride, use a small day pack bring a lunch, water, something to write on, a camera, in case the talisman cant be carried home...
It will forever be tied to your birthday.
And I am sincere, life gives us these opportunities to explore, for some it doesn't come very often. Time alone, is best to quest and journey...