Hi I had the same problem with my mum. in the end I bought a cycling Id band which has an engraved metal plate attached for name ,house no & postcode, emergency numbers and I had memory impaired added to hers. I told her it was important that she never removed it , fortunately she never did. The police found her wandering at 4am and were able to take her home.
I cannot post a link but its iceid.co.uk