Here’s a list of all federal benefits that undocumented immigrants are eligible to receive:

https://www.ncsl.org/immigration/federal-benefit-eligibility-for-unauthorized-immigrants

States may or may not have additional programs.

I literally know an elderly lady who is alienated from her family in Europe and lives in California without any papers, money, or a job, and she has her own apartment and makes due somehow.

No I’m not saying she oughta be deported or have her benefits cut or anything (she’s not living a particularly glorious lifestyle, believe me), just answering the question that was asked.