Supplemental Health Insurance for Seniors with Limited Income: Is It Needed?

Question
My father(80 years old) has limited income and no assetts.  Is it necessary for him to have the suplimenatary health insurance when it is hard to afford and he has nothing?  Will he be denied any health care and in case of emergency, who is resposible for the additional expense?  Thanks for your time.

Answer
Is it necessary for him to have the suplimenatary health insurance when it is hard to afford and he has nothing?
Not really if he lives in the US, Canada or England.

Will he be denied any health care and in case of emergency, who is resposible for the additional expense?
The state is responsible as long as he has no assets what so ever.