Fair Housing will want proof. A letter from the MD recommending the help would be a start. Then the helper presents their certifications/training/licensing to establish their appropriate skill set.
I don't understand your question. The Fair Housing Act is an act that makes sure there is no discrimination when someone wants to rent or buy. It has nothing to do with hiring a caregiver. If someone needs a caregiver, they can hire one...so I'm not sure what you need to know. could you give more information?