An interesting liability question

[Rick Beno]

I have a wonderful family living in one of my large single family homes.  A few weeks ago the tenant informed me that her mother (who lives elsewhere) had taken a fall and broken her hip.  The mother would be in rehab for several weeks at a hospital and then would come and live with the tenants for five or six weeks until she could return home. 

Of course, I offered my condolences and that I was glad the house had a main floor room and bathroom that would be so helpful.

However, now I am wondering about the liability I might incur on this.  The bathroom has no handicap bars or any other special safety devices; the lease makes no mention, of course, of this additional person living in the house.  

I have no desire to refuse this request (and it would be unreasonable and unkind to do so), but I am wondering if should write up some kind of paperwork for it.

Thoughts?