My parents have been US permanent residents since the 1980's. They lived most of their professional careers abroad and then retired. They have since moved back to the US and as their son, I provide them room and board and take care of their basic living expenses. Their investment income that was supporting them through retirement has declined significantly for various reasons. Healthcare expenses are eating a significant chunk of their savings. Given that they spent a lot of time working and living abroad, would they qualify for Medicaid?
Because there are special circumstances, your best bet would be to consult an Elder Law Attorney who specializes in Medicaid. Each state has their own rules and regulations and an attorney would be familiar with the ones for your state.