I would normally say that I'd prefer my own space, so would opt for two separate rooms. That being said, it would possibly cost more to do that, and having a kitchen and your own washer/dryer for two weeks would be more enticing to me. I can only eat out for so long after I just want a little sandwich or something small and plain. I enjoy having wine & cheese or something in the evenings, so it is nice to have the larger refrigerator for that.
I find the sofa sleepers at DVC rooms really not too bad! They're much nicer than at the Marriott timeshares (I'm a Marriott owner). So you could use the sofa sleeper and give your mom & her love the master bedroom.
It's nice to have the washer/dryer at your disposal. We use them daily when we have them!
For Christmas dinner, to me it would be nice to order from Publix or another local grocery store something like one of those fully cooked turkey dinners that you just reheat. It takes a couple hours, but may be fun to do so! If you don't have a rental car, you can just use taxis or an Uber or Lyft to go to the store. Likely if you do the villa, you'll want to stock up on essentials anyway!
I don't mind cooking on vacation, although on Disney trips it's more often easy things like sandwiches, breakfasts (biscuits, eggs, etc.), or things like Stouffers meatloaf (yes I did that once, when the kids were young). I also grill, but that's at Marriott timeshares where they always have gas grills available. It seems like the Disney ones have charcoal, and that's just too much work!