I understand completely. Even with 2 sister's in law, myself and my (now ex) husband, we couldn't always keep my mother-in-law safe. The night we were all there and my f-i-l still managed to sneak into the garage, fill a pail with gasoline, walk into the living room and attempt to put the fire in the fireplace out with the gas... that was the night we realized we needed to put him into a home for altzheimer's patients.
It was a tough decision but we had to accept he was a danger to himself and to us.
My mom would hear voices, and tell me people were in the living room with her .. and they wanted to take her home. I knew that if she went out on the porch in the dark, she could fall down the stairs. She didn't have any concerns about it - which tells you they aren't in touch with reality.
It was so difficult. Now that she's in a lock-down facility (but I'm allowed to visit any time I want), I feel much better about her safety.