What liability do I personally have for my mother's reverse mortgage in the State of Florida?

Probably not, but there are too many variables that would need to be addressed before a direct answer can be determined.  Namely, I’d be interested in taking a look at the reverse mortgage paperwork and the civil summons.  Generally, the only “liability” you would be dealing with is the loss of the home per the reverse mortgage.  To be sure, I’d advise getting a consultation with a local real estate or foreclosure defense attorney where you can have all of the documents looked at and discuss the details.