My MIL has roaches 😷

So I'm a major neat freak and my MIL...not so much. My DH and I are staying with her for a month because we have things to take care of in the town where she lives and we are I've 3 hours away. While it's very nice of her to let us stay with her, she's a total slob. She doesn't clean (I'm not sure she even knows how) and she has pets that she'd like crazy but doesn't even own a vacuum. I can handle the messiness. I actually enjoy cleaning really dirty things. I even cleaned out her disaster of a refrigerator and threw away food that expired over 3 years ago (when she moved in to her home). However, there is one major issue that I absolutely cannot overlook. She has a serious roach problem. She also refuses to acknowledge how bad it really is. We told her that we see tons of them and she makes up excuses and blows it off. I understand that exterminators are expensive but she needs to do something. She has them because she leaves food out and doesn't seal anything. She made steak the other night and when I opened the fridge it was on a plate with a Walmart bag around it. She leaves things open in the pantry and like I said, she doesn't clean so there were crumbs everywhere before I swept and she doesn't own a mop so when she's gone tomorrow I'll be on my hands and knees cleaning the floor with a rag. I'm worried that when we have kids I'll have to tell her that I don't want them at her house unless she starts cleaning. I know it's old habits and all but it's so bad. There's a big difference between being tidy and being clean. She tidies up regularly but never actually cleans. How can I try and take care of her filthy home without offending her? If I have to stay here (and I really don't have any other options) I at least want to be comfortable eating food from the kitchen.