Neither of those really solve the problem. If she gains legal status, then cool, she gets free treatment for her retarded self-inflicted problem, but at who's expense? Taxpayers. And I don't think third world countries are all that great at treating people with first-world medical issues.
The best solutions here would be A:
Get a job and pay for it herself
Or the pessimistic option B:
Die
I didn't say the problem would be solved, just hers.
Also, don't underestimate Mexican healthcare, it often outperforms American care. In this womans case it would definitely be better than what she has. Dialysis is not a first world technology. A quick google appears to show plenty of locations available for this.
It sounds like her problem would be solved by obtaining legal status, or going home.