Add to 403B or take over mom’s mortgage?

My mom is on asocial security and gets around $900/mo. Her mortgage is low, about half that amount and still owes about $85k. I could pay her mortgage instead of contributing to my 403B. If I don’t she may need to sell due to inflation then use that money to rent a place, hoping it’s enough to support her. Selling would net her at least $300k. I feel if she sells any inheritance I would get would be diminished over time through her living expenses. If I make her payments I’m practically guaranteeing the inheritance at the expense of contributing to my own retirement. We live in the Bay Area and housing/real estate is expensive. Selfish question: will her home be more valuable than retirement contributions over a 10 year period?
Thanks in advance for the helpful comments.