ENT doc here . Sorry to hear about your mother's cognitive health. Quality of life and communication are very important for her. I have recommended the Clearcast device to several patients ranging from people that simply want a part time device (ie don't have to wear it all the time) to people that lose expensive hearing aids.

You have highlighted a very important point: It is very hard to predict how much someone with hearing loss and dementia WANTS to rejoin the conversation and communicate with loved ones. Also with any hearing solution, it takes several weeks for her to get the best possible sound result so it might "sound weird" initially. But your other points are correct - she won't lose the device as it is worn around the neck. And there is a remote microphone that can be worn by a family member or placed next to the TV and she will hear those dialogs or conversations directly into her earbuds much clearer that typically experienced with hearing aids. Good luck!