( I'm a bit surprised that nursing home cost is "only" $4000 per month. In my area (Wisconsin) it is $9 - 10K per month, although assisted living charges range from $3.5 - 5K per month. It is possible that Medicaid is paying the difference.)
>> FYI: For your planning purposes, 2019 medical expenses deductions will be limited to 10% of your AGI. Plan accordingly. <<
If you want to be proactive, you can contact your US congress person and Senators, giving them the same details you wrote here and explaining the results, and the impact of those results on this person.
If you find a better result, please update this thread.
The new tax law for 2018 eliminated personal exemptions, and increased the standard deduction.
In 2017 the personal exemption was $4050 per person (more for over 65 or blind).
In 2017 the standard deduction was $6350 (single) and $12,700 joint.
2018 standard deduction is 12,000 single, 24,000 married (with adjustments for head of household and over 65 .. .)
If the person's marital status changed, or if they previously claimed many dependents, it is mathematically possible that 2018's standard deduction does not offset the loss of personal exemptions.
However, a Medicaid recipient, living in a nursing home would likely have lots of medical expenses, which would likely exceed the standard deductions.
My suggestion is to review all the entries you have made for income, and deductions. Look for mistakes in entry or perhaps double entries. Pay special attention to the medical expenses. Also, look to see if the SSA payments are being treated as not taxable. Check to see if the standard deduction is being taken or the itemized deductions are being used. Also ensure that the correct filing status (single or married-joint) is being used and matches last year's returns, if appropriate.
If this does not resolve your question, please rsvp with details of your findings..