How to cope and protect my mental health?

My Mother in law is 72 years old , resides in the Dominican Republic and comes to the US to visit her adult children and to go to the Doctors. She stays in my house for a month and goes to medical appointments in another city 4 hours away where her other Son lives so she also stays there as well, sometimes she has stayed 5 months between the 2 houses. My husband is the nicest and most respectful , she has another son that lives 10 minutes from us but he is very mean because he looses his patience due to her constant questioning and wanting to know everything, she only visits him for a few hours. Her tenants contacted my Brother in law because she is yelling at them and accusing them of stealing her internet, electricity and water. She calls me and all her children explaining that the tenant goes to her roof during the night and doesn’t let her sleep connecting his electricity cables to hers. This is a constant topic of conversation, I try to change the subject and she manages to go back to the same thing. My brother in law the mean one tells her that she is lying and that he is taking her to see a Doctor. She refused so now he is coming with her in 2 weeks and she will be staying in my house as always. I work from home, just had a baby who turned 3 months and have my 8 year old daughter. It’s very stressful because I have to cook all meals when she visits, Maybe my husband told her something in the past because she was too messy so she doesn’t cook anything and asks permission if she wants to eat. I keep telling her please no need to ask, all the food here is yours too. She asks the same questions and really stresses me the entire day asking me questions about her cellphone, or personal questions about my household etc. or asking me why I didn’t serve my husband dinner, or telling my husband why I went to my room if something is wrong? I went to my room at the end of the day because I was pregnant, tired of work, cooking and her constant questions, so when my husband came from work is more than fair he also entertains her as well. I keep telling my husband all of them need to take her to get checked but he says that he doesn’t have time, and that she has been like this all her life that it will be worse if she gets medicated etc. sounds like he is in denial, I don’t understand. I feel like no one wants her in their house. My brother in law told everyone that he was taking her to see a Doctor he has not done so because she doesn’t want to. He did convince her to come with him to the US so he will bring her just like that and has not mentioned if he will take her to get checked or not. It would give me a breather if she also goes to his house to visit during the day for a few hours , his wife does not work and stays home with a 4 year old, but because she does not feel welcome she stays in my house. How can I protect myself mentally so I don’t end up sick? I don’t want to have problems with my husband because he loves his mom but some one needs to be responsible and take her so see a Doctor. Any suggestions I can give my husband so he takes it serious? Also her son who lives 4 hours away is now saying that he doesn’t want her to stay in his house because he will be having guests and he feels embarrassed because she makes a mess in the kitchen and there are always fruit flies. She actually cooks there because this son works traveling away from home with his wife. I also have a sister in law who live in Vienna very far and has 2 small children, she said that she will make arrangements with her husband so she can come and take her mom to see a Doctor, but again I don’t see that happening either. I feel the same thing will happen. She will be in my house driving me insane. Is there any medication? What typically happens in this case? We don’t even know if she has Dementia or Alzheimers but I wonder if when she comes to my house maybe she will not hear her tennant in the roof anymore but will probably lie that I am not nice to her.