It only takes one incident (which I am sure has occured at least once in the many nursing homes) to make everyone wonder why it was ever allowed in the first place.
To reiterate, that is why nursing homes have smoking lounges. They usually round up all of the smokers and have a nurses aide watch them during smoking breaks. The residents then return to rooms or other activities. The cigarettes and lighters are kept at the nurse's stations. There is no safety issue because the homes don't let residents smoke in their rooms.
As a medical student I remember my nursing home rotation. There was a guy in a wheelchair who smoked. They kept his cigs, lighter, etc. in the desk, and had a special asbestos bib that they put on him whe he felt like a smoke.