I second the idea to ask her what ingredients she needs for her pumpkin pie and get them before Wednesday. How much of a mess could she possibly make with that dish?

Figure out what is non-negotiable for you, and then let a few other things go. What is just you being stubborn because your MIL is a PITA, and what is a real issue?

Maybe your sofa is more comfy than your guest bed. I say just suck it up since it's just one day.

I'm sure your MIL could write a paragraph rant on you also.