The symptoms depend on which part of his brain was affected by the stroke. While Alzheimer's usually begins with memory problems, vascular dementia more often begins with poor judgment or trouble planning, organizing, and making decisions.
Landlords are not responsible for the loss of personal property of a tenant after a fire. This is because the landlord had no control over the fire or over what property the tenants decided to keep in the rental unit.
If you have no personal property in the building besides appliances, get a rental dwelling policy. My insurance guy said that my insurance would not cover willful damage to the house on the part of the tenant. If the tenant set fire to the house, the insurance does not pay.