Definitely try to get her to surrender them -- to you, to a shelter, to a rescue. Calling the police usually just brings in animal control. And unless you live in a city with a no-kill shelter, that's a good way to get an instant death sentence -- particularly for an animal that is in the condition that you say these three are.
My experience with animal control is that they are solely animal
movers. Move from the home or from a neighborhood street to their truck, to a pen, and almost always to execution in a week or two. (Unless they have a no-kill shelter. Most cities DON'T have this. These are run by privately funded organizations.)
As for selling them ... tell her she is just opening herself up to neglect reports. And that can lead to the troubles you mentioned earlier with eviction.
If she's your friend, you should be able to be honest with her. And if she truly cares about these animals, she will let them go.
In any case, I feel for you. You are in a none too enviable spot.