So last night at about 7pm my mother showed up, on foot, at my sister's house. My Sister lives about a 1/2 a mile away from my mother. My mother walked from her house to my sisters house in her pj's and slippers. It has been raining all day so her slippers were soaked through. She said she came because she said her phone wasn't working. When my sister checked the phone was working just fine.
Is this wandering? She remembers doing it. But walking to my sister's house in her pj's and slippers, isn't good judgement... but would it be considered wandering?
I'm also not sure that whether it officially constitutes "wandering" is the issue, which really is that your mother wasn't able to realize the phone was working, made an unwise decision, and didn't realize that it was unwise and unsafe.
Does she have a Medic Alert pendant? It wouldn't necessarily stop her from wandering, but it would provide a level of safety if she were to fall, especially on slippery sidewalks or pavement, or even grass.
Does she live completely alone? Are there any cameras at her doors that could be monitored remotely? What stage is her dementia?
So even though she remembers walking to my Sisters house the fact that she didn't think to get dressed or even put walking shoes on constitutes wandering?