I've been thinking along the lines of @kuzenkohome 's idea --add some tried-and-true sensors to the array. Maybe contact sensors on her bedroom and bathroom doors, fridge door, and kitchen cabinet. Flow sensor on the water main. I'd suggest switches but my guests hate smart switches.
How are you planning to report lack of activity and send notifications? Something like Bptworld's Device Watchdog app (no longer supported) might get close to compiling the report but notification?
Device Watchdog'
Create Activity reports based on number of hours since the device checked in.
- Choose whether to show devices that have been Active or Inactive within the set number of hours.
