Social Security Questions? Ask a Social Security Expert
It could be that your mother in law is on Medicaid. That is the government is paying for her long-term care expenses including the nursing home costs. Therefore, she is only allowed for small amount such as, $30 or $60 personal allowances monthly for her personal expenses. The social security paid over to the long-term care facility is her co-pay, "share of cost", for the long-term care facility cost.
The enclosed link to the government website on long-term care program such as medicaid, is attached for your further reference.
Please feel free to follow up.
Fiona Chen, MPA, PH.D., CPA, ABV, CFF, CITP