They might ask about ADA compliance, number of parking stalls, designated Handicap parking, do you have grandfathered in fire suppression, etc.  

Making one apartment ADA, creating another form of egress,  upgrading the insulation to the required r value the list goes on.

He stressed the importance of it being ADA accessible so larger bathrooms and specific ADA Standards, but they pay more. 

There are quite a few nuances, but much of this is covered under Federal Fair Housing law and the ADA.

@Steven Medaglia if they’re a good tenant I would allow the mother to move in and add her to the lease.In accordance with the ADA (Americans with disabilities act) you MUST accommodate their request to modify the property for handicap accessibility but you do not have to pay for it and can require them to return the property in its original condition when they leave all at their own expense.Good idea on the licensed contractor part.

You will probably need to look at Commercial policies (Business Owners or Package policy).Another consideration is the ADA compliant changes that are required for that use.

Aloha,"Service dog" is an ADA definition, which applies to public/commercial spaces.

One of the requirements to pass inspection,   regardless of when the structure was built,  is that the hand rails meet all current safety and ADA standards it turns out.  

In most cases, landlords are required by law to make reasonable accommodations for tenants with disabilities under the Fair Housing Act (FHA) and the Americans with Disabilities Act (ADA).

I think my biggest concern is or was ADA and how that applies to 5+.