Start with Christmas pjs then she can wear them in the build up too.
personal promise vouchers:
baking day
mum and daughter shopping trip
fancy popcorn and promise of a movie night
mini bubble bath and face mask, then run her a bath.
tickets to a local event/show.
There are loads of really good ideas and deals on the bargain thread and you could pick up on some of these.
Lego set to build a Christmas tree or something that she can get focused on. I am just presuming such a thing exists!! My dd got back into Lego sets again when she was stressed and anxious at uni a couple of years go (same age).
We also bought one of those cold case packs and it was more complex than we expected! Really good fun though and took up the evening rather than just an hour like I’d expected. DD has asked for another one this Christmas.
There are also those escape trail things in lots of cities - could do one of those or the free clue solving ones you can get online. You could go somewhere nice and Christmassy if there’s anywhere like that locally to you.
coukd you set a Christmas present challenge or plan to do one of those Christmas Day games people talk about on these threads? She could be given the job of organising it and getting all the presents bought within your budget. I can’t remember the games but if you did a search or asked people come up with loads!
get her involved in the Christmas prep, decorating, baking, planning the menu.
Plan a trip to a Christmas market and look for cheap flights, we got to Prague for a day at the Christmas markets for cheaper than it would have been to go a big one near(ish) us.
give her jobs like selecting and making a family photo calendar for grandparents which will also help her focus on happy events from the past year.
There was something else I was just about to type but my phone rang and it’s gone out of my head!! 😂 Menopause memory. If I remember I will post again. Just trying to remember things that helped my dd.