No matter what you go with, don't say you were sick.
Bad move, while employers can't fire you for ill health (mostly) they sure as hell won't consider you. They have to think of the business and it does not make good business sense to hire someone sickly who was unemployed for years due to illness.
You'll look like a liability instead of an asset.

This is one of those times where honesty will get you nowhere and lying will hurt nobody.

I personally vote for caregiver, its a half truth because you were the patient, so not as bad as outright lying, which alot of people do during interviews anyway.