Does my elderly parent need a supplement to Medicare?

It depends. Supplements can be very expensive, particularly if not selected during the initial enrollment period. You have to weigh the cost of the insurance against the possible benefits of it, then make a decision. Different policies cover different things. Without knowing about the health of the person and the policy being considered, it's hard to say yes or no.

I agree with "yes". Look around for a Medicare supplement plan, maybe AARP, something like that. My mom had one and both Medicare & her supplemental covered close to everything. My mom had several high cost medical events as well; hip replacement, mastectomy etc.

I would think the answer is yes.

They can only sign up during the once a year annual enrollment. If thy get real sick and need a lot of medical care....if they don't have the insurance...they have o wait till November to sign up...meanwhile possibly very large medical bills could result in bankruptcy.

It depends. Do they have a lot of prescriptions? Do they have a lot of doctor visits or therapy that require copay? It's a different answer depending on your own parents situation.