It depends entirely on her health. At 72, she could be just as fine with hot stone as you & I, or she could be on multiple meds and have very thin, easily burned and torn skin. If she is asking for hot stones, she probably knows what she is asking for. I'd start with asking if she has had this done before, and if so, did the stones need to be cooled any before applying them (or a sheet put between the stones and her skin). You will have her health intake, so go over that carefully with her.