It's sad to hear that a ***** would do that to a parent. Sorry to hear about that B/C.
As for refinancing and paying off the reverse mortgage, unless it's a much higher interest rate than the refi, would she be saving enough to make it worthwhile? I've not dealt with a reverse mortgage situation before, but I do know that they tend to be loaded with fees and some are just straight rip-offs.
But your *** would have to qualify for a conventional mortgage based on income. If she borrows $150K for 15 years at 4.5%, she'd need about $4 grand a month in gross income to qualify for a conventional mortgage (course, one or all of the **** could also go in as co-borrowers). $150K assumes that she uses what's left of the extra $25 grand to pay the closing costs, and whatever fees or penalties that might be attached to the reverse. The closing costs on the new loan will probably run somewhere between $5-$7 thousand, depending on how many points she pays and what other fees are standard for your area.
But if the combined costs of getting out of the reverse plus securing a new mortgage make this impractical, maybe it's not so bad... since it sounds like your *** has now basically made this more like an advance on your ******'s inheritance. Still, that was a pretty crappy thing to do, IMO.