MIL sold her house in So. CA. and then bought a house in NO. CA and paid it off instead of getting a mortgage.
Now she struggles and scrimps and saves to pay the insurance and property taxes.
She's 84.
Is there some way she can reap the equity without leaving a legacy of debt?

Check out the reverse mortgage option but read and study carefully. It is a viable option. Instead of paying on a mortgage, they will be paying her. The reading involves fees plus heirship questions, etc.

reverse mortgages are usually a rip off and should only be a last resort for someone who is cash poor but assett rich and wants to remain the home until they die.

I say they are a rip off because of the HUGE fees.

I've heard about those huge fees, don't know what "normal" fees should look like though.
She wants to remain there although we think she should sell the place and go into assisted living.
We can only give her info and make suggestions, but we can't walk her through anything.
Her middle son takes care of her finances and so far he's done one huge bonehead job of it.
I could tell you some stories, whew!

prior to my father's death, when my parents looked into it the "reverse mortgage" would only be about 60 percent of the equity in their PIF home.

My mother did this, owned her home free and clear,paid cash for it,,valued at 185k, she got around 90k on the reverse mortgage...

Is she still living?

If there is any chance that she may need to move to a facility (assisted living or a nursing home) do not do the reverse mortgage. Many of the elder care lawyers I deal with (I'm a social worker in a nursing home) do not recommend reverse mortgages. I've seen some people who really need 24 hour care in a facility in a pickle because of reverse mortgages.

I need to warn my parents about that. My dad has mentioned that he would like to check into it.

Yes, she is still living and in fairly good health pushing 70....