1.LIS is low income subsidy.
Under Part B it is called QMB & SLMB. Social security would cover the 97.50 monthly premium and some of the co-payment.
Income is below $850 a month. i think. check medicare.gov for the details.
Part D has whatis called "EXTRA HELP". agian go to medicare.gov. EXTRA HELP has 4 levels of income.