For a traveler aged 85 years, there are only a few companies which offer insurance for overseas travel. Therefore i'm suggesting the following plans:
ICICI Lombard offers coverage for $25,000 and $50,000.
Trawelltag's National Insurance offers coverage for $50,000 and $250,000.
Bajaj Allianz Insurance offers coverage for $50,000.
As the traveler is 80+ the above companies have medical subimits (capping). You can purchase the policy online by filling simple online proposal form and without giving any medical reports for issuance of policy.
However Bajaj Allianz provides an additional option where the traveler can purchase the policy online by submitting medical reports.
NRIOL Customer support.