How are foreigners in the US caring for sick parents?

My mom who is a single parent is suffering from a lot of diabetic complications : damaged optic nerves, high blood pressure, high heart rate, swollen feet etc.
She lives in a third world country and I don’t think they will be able to give her the best healthcare there.

I want her to come to the US for the next couple of months but my insurance doesn’t apply to my parents, so she’d have to cop the bill. She only has $150k in savings. Half of which she plans on putting in my sister’s education in the US. Leaving her with less than $70k of disposable income.

I’m willing to put in an extra $30-40k for any medical emergency or surgeries that may come up. Do you think $100k will suffice for all costs without insurance? Last year, I had a surgery that cost $170k (covered by insurance) which is why I’m not confident in this funds.

How are you guys caring for parents in the US with no insurance? Any suggestions?