Axure, I understand completely where you are coming from, and it is very hard to say no and set boundaries, especially once Mums are (not elderly but) older and expect their grown-up and mature children to still run around after them, and no traditions shall ever be broken again!!
If you do have to have your mum this year, try to set the boundaries before she comes, letting her know that you will be going out to A's house on Mon morning, meeting B&C for drinks on Wed evening, and having D, E & F over for a meal on Fri. But you will also be booking tickets for the carol service in "Ye local heritage spot", would she like you to book 1 for her too? Of course she will be eating with you all on the Friday. Perhaps we could go together to (beautician/hairdresser/nice coffeeshop) on Tuesday late afternoon after work? ...... And you recognise that as she's getting older, while she might like to come to event M, N and O, you realise that the party on NYE might be too much for her so you are planning on having a nice platter of nibblies and a small bottle of champagne for her to welcome the NY at the hour of her choosing at home, we'll try not to make too much noise when we roll in in the early hours.....
I'd also have some coping strategies for when she is in the house with you all. That you have your lists of things to get done yourself and get through them, let her know which programmes you really want to watch on tv, and make sure you have some space in the day to chat with her too (even if it's over the kitchen table while you peel potatoes). Get an old-fashioned kettle for the cooker, so she can make her own tea when she needs it. Do a (secret) list of jobs that she could do that would "really help me out Mum, you can see how much there is to do", when you need a distraction. Even have a few that you can flatter her and play to her strengths with - like if she's good at arranging flowers, ask her to do some for the table, or for the hall (if you'd prefer to do the table yourself). Or set the table for dinner, do some of the cooking (any particular specialities?), help DS with his wrapping ("boys are all thumbs, aren't they"), .....
And I don't know if this IS possible, but maybe try to make her room really comfortable with a chair, nice books, radiator on and cosy, lap blanket, basket of snacks, radio or CD player or even a small tv, maybe some nice bath bubbles....so that she has somewhere nice to retreat to. Or have a place you can send her downstairs (like lighting open fire in living room early in the day or as soon as you get home rather than later in the evening, having candles lit there, nice music or tv available...) and sending her in with a nice cup of tea to relax while you get a few things done and will join her later. And also having some space somewhere that you can retreat to as well (even if that is having candles, music, a book and some really nice bath stuff in the bathroom to sneak in with a glass of wine for a half hour).
I know that probably reads patronisingly and it really isn't meant to be, just a few things I keep saying I will try and some that I have for similar circumstances.