To want to stop paying all Xmas hosting costs

Physically and mentally are important aspects: the having to do everything, irrespective of the cost, from breakfast to supper (incl for randoms) for days on end! Planning entertainment!
It’s unbelievably selfish of these people to take for granted such a performance and expense for a feckin decade, and not even offer to give OP a break, never mind a bottle of Champagne for her exhausted self. .

What do your mums neighbours and friends do for her during the year op. ?

oh god no. 10 years of paying for Christmas is enough!

OP isn’t a professional hostess and entertainer! It all sounds utterly exhausting, and would do were one a mere slip of a girl never mind a woman in her late 50s.

Send them to Butlins (they pay!) if they want this all-in catering/rave up holiday scene.

Seen your update. Good idea.

I don't think I would ask for contributions. Just cater for you and your Mum or make other arrangements. Too awkward to start asking for donations imho.

Excellent plan. (Ensure she knows it’s either your place or no OP at all.)

I don't think this needs to be a difficult conversion at all.... all you need to say is "Mum - I ended up spending £500 on xmas food last year, and I really can't afford to do the same again. What do you want to do instead?".

Brilliant idea! And her other daughter will be there, no?
That threesome could be very inexpensive yet very enjoyable, with nothing omitted that they all love at Christmas. Sounds smashing to me.
(Those neighbours and friends of her mum can shift for themselves, no doubt, but best be ready to repel any last minute suggestions that they come along too)

Your mum's a piss-taker, sorry. She can't be unaware that you are footing the bill for not only her but several hangers on. I'd never let my child do that. I could understand you paying for your mum if she's in tough circumstances, but the neighbours etc? They are piss-takers too. That's outrageous.

Usually for the four or five of us, but more for events.

Blimey!

To coin a phrase, I think you need to check your (financial) privilege.

Do you really think 10 years of freeloading by the OP's mum's friends and neighbours is acceptable?

Yes totally.

And yes it's expensive, especially if it's not just Christmas Dinner. We don't spend a huge amount as my family is small and we don't eat that much either, but if you want a decent free range turkey that is over £100 alone, before you've bought the veg, the pudding, some extra alcohol if you drink it, chocolates etc.

Shes your mum and unless you don't want to say then I take it you had a decent upbringing or you wouldn't want to make an effort. It's none of your business how much money she has. And £500 could be saved up through the year. We host Christmas and that week when everyone is in & out. My dad comes over with his "companion" I know they are loaded but I never ever complain or suggest any guest brings anything. Why is everything so monetised these days no more family time or enjoyment just complaining about costs! If you really can't afford it just tell your mum that you don't want to cause problems but your skint. Otherwise don't gripe about it just get on with it & enjoy Christmas with your mum while she's still with you

I think that is very sensible. You’re basically paying for Christmas for several other adults. Do none of the neighbours contribute anything? Seems incredibly cheeky if they don’t.

The thing is that as we're now in the run up to Christmas (!) you need to sort this quickly, so you can nip everyone's expectations in the bud. No need to make a huge thing of it - but you have to tell your mum that Christmas has to be different this year, as you can't afford to pay to host/entertain everyone. So it will be family only, and she's going to have to share the cost. Even your sibling should be asked to make some kind of contribution.

If she still wants to go ahead and entertain friends and neighbours as well, then she will have to pay for that.

Be firm and stand your ground!

We had 14 for Christmas day last year, and a fair few on Christmas Eve. Our food bill was nearly £700 and I'm just not doing it again this year. Sod all the baking and days of preparation - we're having a roast dinner, with a nice pudding/cheese board after and if anyone wants anything else, they can bring it themselves. My food shop budget is £300 and I won't be going over it.

Sorry but that can’t be much of a dinner for 16 people… Food must be extremely cheap in the UK, maybe I should go and stock up!
A pity with the tourist tax.

From the way the OP is written, it’s possible that the mum has lost track of how much things like Christmas costs. My mum is 80 and is perpetually astonished at the price of things - she still thinks it’s the mid 90s.

It’s so easy to spend £500 over Christmas Eve to Boxing Day. You don’t even need that much booze to get to that figure. The turkey / goose alone is well over £100 from the butcher.

Yeah. Just say with changed circumstances and the cost of living etc. you simply are not in a position to be able to pay any more. You dont have to be nasty about it. Of course you don t have to be involved at all, but if you want to do things in a kindly way just be honest. If they all then get shirty about it then thats their problem.

When you've made those sorts of efforts for years and no one has thought to offer to help either financially or practically, it comes to be seen as "the way things are" and when you stop things from being "the way they are" because you're exhausted/broke or whatever, people don't generally think "blimey, she did all that for us for a decade", they tend to think along the lines of "where has my Christmas gone?" Just warning you - be prepared for some awkwardness.

You do need to say something OR stump up £500 and go home with a ton of resentment. Those are your two choices here.