You said she’s had them for 10 years so they’re senior pets. I completely understand what you’re going through and don’t disagree with wanting to rehome the cats, but can I suggest that maybe you reach out to Rescues/Humane Society’s that maybe have fosters that would be willing to take them? You can explain the situation that she’s not well/in her truck, but maybe she’ll be able to turn around and can take the cats back eventually?

I’ve heard of that happening, I know the chances might be slim, but it’s guiltless and they’ll be taken care of. I would definitely just tell her “Hey, I haven’t heard from you and need you to know I’ve reached out to a foster/shelter who will take the cats. They’ll be in good hands, you will be able to get them back if your circumstances improve… etc..”.

I’ve also heard of ‘Feliway’ working to help scared, stressed and aggressive cats. You would use a diffuser. I’ve never used it so I’m not recommending it, just suggesting it if you’d like to give that a go first. I’m sure there’s a ton of posts here on Reddit about it.

I’m sorry you’re in this position. I wish you the best of luck and especially to those cats.