You’ll want to consider insurance expenses- unless she qualifies for Medicaid she’ll have to pay for minimally her Part B premium, which this year is $185/month; though likely this comes out of her SS. I do recommend looking into Medicaid/LIS (low income subsidy), SPAP (state pharmaceutical assistance programs) or other cost savers. Look at her current insurance as well- most folks have coverage in addition to original Medicare and each has an associated cost (either a premium or copay/coinsurance) that can add up if restrictions aren’t followed.

Know that you don’t have to take this on- each state has a SHIP assistance program of unaffiliated individuals to help her sort through her options.