Hi K.,
After being in labor allday, I ended up delivering via Caesarian. It went really well, and I had no problems. Still, there are restrictions, and the newness of the motherhood experience that makes me sure that you'll really appreciate the help - even if your mother-in-law is a bit of a challenge. That said, too much help will make you crazy and help for a short period can make you feel forgotten.
My in-laws live nearby, but my parents flew in. All were at the hospital when my baby arrived, but they weren't around much during the rest of my hospital stay, and I was worried about my parents being bored, thus, my husband got split in two. I was so glad that my parents stayed for a week after I came home. When they left, my hubby was back to work, and I felt really lonely, and a bit lost. While the baby slept, I wanted to do the things that needed doing, but most were against doc's orders. Thus, I was glad for the visits of my in-laws, even if all they did was hold the baby and ignore me. It made me feel good that they thought she was so special, and it gave me a bit of company.
Based on my experience, my thought is to tell your mother in law that you want her to come for a week, or some tolerable amount of time. Tell her that you also want your mom to come for a week, but you want them one after another. Tell her that your mom is coming from the 29th for a week, and if she could come after that you'd be in heaven. You won't be able to drive, and stairs are tough, you'll need laundry done & cooking, and vacuuming because your doc won't let you do it and your husband will be busy/working. Tell her you'll have a special Christmas with her when she arrives, and it will give her one-on-one time with her granddaughter, her son, and you! And, by the way, maybe have your mom come after Christmas so you and your hubby and share this last one together. And don't forget, you won't be released from the hospital for 3 or 4 days, so any of that time that someone is in town will not benefit you (or them) too much. Trust me when I say you won't want visitors in your room 24/7, and you'll have discomfort and will likely be tired. There will be so much activity in the hospital with nurses and docs always checking you and/or the baby, you won't get very rested, and you won't be up to entertaining in your room. (You could also consider having your MIL come first, so 4 days that she's there, you'll be in the hospital and won't have to deal with her much:-)