@Cleverchops I'm on the fence.
From 1995 to Covid I made a rod for my own back and we had the ILs every Christmas. They always came.for a week and had to be hosted three meals a day. I used to joke.that by our silver wedding anniversary MIL still didn't know where the fucking kettle was.
However, they always came by train. When we lived in London the tube bit was easier but once she was widowed I started dropping her at South Ken so straight on the Piccadilly line to Kings X. Once she turned 80, the train journey worried us more when she was on her own.
In her very late 70s, we moved out of London and until Covid, DH and DS met her from Kings X to help with bags.
Whilst I think previously your mum should have caught the train, if she never has, now might be too difficult.
MIL (and my mum) are 90 now and increasingly frail. Post Covid neither have been able to make the journey and step stopped driving except locally about then.
For the last few years, DH has spent Christmas in the North with his mum. I spend it in the South with mine. We have felt that Christmas might be their last for a few years now and that is getting closer.
We have our family lunch a week or two before.
I think if your mum's generally well, you should go on holiday, providing she won't be alone. Ours would if it weren't for us, but there will be limited Christmas's moving forward and if I were you I'd keep your guilt minimised.
Have you thought about renting a cottage for Christmas, not too far from your mum's? We did that for a few years until I had to start going to mine.