Well would you want your mom to stay with you when she has problems, if yes you have to let his mom stay too.

How big was that cheese sandwich?

So Holiday Inn Express is all booked up?
If your mother in law moves in, It will be the end of your marriage and walking around in your shorts around the house

The cheese caused you to fart in your sleep so badly, your wife called her mom. This woke up her husband and caused the fight that brought her to your house.

Therefore, cheese eaten late causes nightmares. QED

Hopefully it was a nightmare and not real

If your spouse offered to have her there without consulting you first, you need to have a serious talk. If MIL invited herself over, get her out of your home. You need to have some stronger boundaries with your MIL if she's entered your room without permission while you're sleeping. Neither of you have an obligation to offer her a place to stay.

Way to put someone on the spot, in-law.

Put your foot down
You aren't a bed and breakfast for months on end

Umm wow anyone who does not understand simple boundaries is either a moron or an asshole,my mother-in-law had keys to our house but would never enter without letting us know and why and would never come into our bedroom when we were sleeping even if it was an emergency she would at least knock on the door first if we hadn't answered the doorbell 🙄😒