“Pay into social security”?
That’s not health insurance. She’s not eligible for Medicaid or Medicare.
You can purchase a health care plan, but I fear you are unprepared for what the monthly premiums could be- potentially >$1k/month.
She may want to reconsider not working, as an employer-based plan is usually the best bet. Or hopefully she has significant savings. If she’s relied on the NHS her whole life, US healthcare costs will be a rude awakening- medical debt is the #1 cause of bankruptcy.
IMHO, it’s irresponsible to make the leap from visiting to adjusting status without even considering these things.