Thats why she needs a more welcoming and kind partner. I know loads of couples who welcome family for visits/ holidays and many too who cared for elderly parents for extended periods of time. Often years if they needed it. It's all part of being married.He doesn't want inlaws living in the house for a week or more. It is his house too so he has some say in who lives in his house and for how long.
If she wants her family to stay for extended periods and doesn't care about his wishes on who is in his house too, that is simply rude and selfish on her part.
I would never subject my wife to having to cater to my friends or family in the house for days and days on end. Heck for that matter I don't even want MY family in the house for more than a weekend. It's just rude IMHO to force your partner to put up with people in the house that they don't want.
Did she ask him if he would be cool with her family staying with them for over a week? Did she ask him for his thoughts and wishes on that matter or did she just assume he should suck it up and deal with it?
What would her response be if he were to just move his family in for a week?
My point here is not whether inlaws should stay for a week or not. My point is it is his house too so his opinion and thoughts matter. His wishes and preferences should be considered as well as hers.
This is something that people should discuss together and come to agreements and plans etc and not just invite people into someone's home without their input.