Don't worry and no need to buy any insurance

You could take your parents to the city or county or some of the public hospital receive govement funding if anything happen and just tell them your parents has no financial resource and no insurance, the social worker there will take care all the govement paper work for you and they will and they MUST treat any patients with or without insurance or money. You just need to make sure don't put your SSN on any of their paper work. Even not emergency, they could still see the doctors there without paying anything or pay very little. So don't wait when they have any discomfort. Call the health service department of the city or county where you live and they will tell you which hospital is city or county hospital. Good luck and hope they don't have to go any of those places.