[anonymous]

Let me guess. Wall to wall old carpeting?
If she is going to have multiple animals in her home, I would suggest having the carpeting torn out and replaced with an easy to clean type of vinyl flooring.
Everything will have to be removed from the house, the occupants will have to stay elsewhere for at least a couple of days so that a professional pest control company can fumigate the place. Anything else would only be a temporary band aid solution (at best) and ineffective.
This could become a Board of Health issue (or Animal Control)……a neighbor could make a call.

This is just my opinion/speculation based on the limited information provided.
I could be way off, but I don’t think so based on what you have described.