I think a prudent course of action would be for her to find some type of employment that allows her to earn the requisite 4 Social Security credits each year for as many years as she can. That would mean earning a little over $4100 this year (and a little more each subsequent year). That means taking the jobs that are covered by Social Security and not the jobs in which no taxes are owed or some school or other government jobs that have their own pension plan. It could mean filing for self-employment if she gets cash only type jobs. At age 22 and under, she would need six credits to be insured for Social Security Disability and after 24 months of entitlement, she would have Medicare coverage for as long as she is disabled. The credit requirement increases every year, but earning at least two credits a year will keep her 'insured' indefinitely.

Now, low earnings do equate to low Social Security benefits and the monthly amount might be difficult to live on. But the benefit of Medicare coverage would probably outweigh everything else in her case. You may always be able to provide her with a home but keeping medical coverage can be very expensive. Medicare supplement insurance can also be purchased, and is much less expensive than buying a comprehensive private insurance policy without Medicare.

If she does become unable to do any kind of work and has low enough income and assets, she could also get Supplemental Security Income and Medicaid which is a big help to the poor disabled. It is a more restrictive program in many ways with more rules. And Medicaid may not offer the medical coverage that Medicare or private insurance offers. But it is a safety net.

Continue to investigate these programs and learn as much as you can. The socialsecurity.gov web site has a great deal of information to read.