FRS = very limited in power and range. Antenna must be permanently fixed to the radio, no range boost by better antenna allowed. Question is whether anyone around her has FRS. Is she in the boonies? Does she have neighbors within line of sight? If yes, maybe she can give them a radio and ask them to turn it on in case of an incident.

GMRS = better than FRS, there are repeaters that might or might not have emergency power, don't know story about acess to the repeaters, license is required ($75/5 years or something like that). No license test, just pay fee.

Ham = repeaters maybe more likely than GMRS to have emergency power, license is free but there is a multiple choice test, external antennas are fine, and if an old lady transmits "I'm on my grandson's radio and I need an ambulance at XYZ address" no one will care if she has no license.

Other possibilities = satellite phone or 2-way pager (yes, pagers are still a thing). These will have monthly subscription fees but maybe she will think they are worth it.

With all of the above, make sure to set up and test ahead of time.

I don't know the situation of cell phone services in emergencies these days. Cell towers do often have backup power, and in times of network congestions where you can't make a voice call, you can often get text messages through. I have felt for a while that the carriers should prioritize this and reserve a little bandwidth for emergency texts, that would otherwise go to mobile data = youtube on your cell phone.

For ham and GPRS repeaters, look at repeaterbook.com to find repeaters near her home, but again, make sure to check access policies and if possible, test ahead of time.