They might want to do it, doesn't necessarily mean they should
Well how bloody patronising can you get.
But the OP's grandmother clearly doesn't have this level of stamina. And that's unlikely to have only become apparent in the last few months.
You're her doctor are you?
I can't believe people haven't been slowly taking over by bringing things for the last 10 years. Poor Nan
The OP doesn't say they haven't.
But wouldn’t it be nice if people looked and thought ‘hmm grandma doesn’t seem quite as spritely these days, maybe I’ll ask if she needs a hand with the Christmas dinner’.
Maybe they've asked and been sent away with a flea in their ear.
I'm astonished at how many posters on a geographically widely used website know the OP's grandmother better than the OP does.
OP it's OK to be sad. When you realise that things can't be the same every year forever, and when you realise that time has to move on and we get older and can't do the things we did. But now is the time to step up to the plate and make sure that you create a magical Christmas for your family. Including your gran. let her know she's leaving Christmas in safe hands.