I talked with my nephew and was happy to learn he'd "lost" his mom's car keys for her.
No surprise, after her 18 hours as a missing person and finding her via a police BOLO notice, SIL was not upset or remorseful. She told my nephew and the police officer that she had been on "a little adventure" and would not say (probably didn't remember) where she had been during that time. When the police officer asked if she would do her a favor and ask her son or his wife to give her a ride the next time she wanted to go somewhere, her response was "Hell no. I'm not giving up my independence!" The cop told my nephew the police could do nothing without something in writing from a doctor.
I was pleased to learn that, in addition to hiding her keys, the nephew and his sister have a plan. SIL has refused to see a doctor for years but has developed an eating problem (hiatial hernia?) that has gotten to the point she wants some help. She has agreed to see a doc and they have an appointment for her next week. The doc specializes in geriatric medicine so they are hopeful he can diagnose her dementia/mental issues as well as help her medical situation. SIL has a LTCI policy and getting the doc to diagnose her should allow nephew and niece to utilize that to pay for some help for her - or get her in a memory care facility.
My nephew's walking on eggshells, hoping his mom doesn't decide she needs to drive somewhere in the interim, forcing an issue with not being able to find her keys. He fears that will lead her to refuse to go to the doc out of concern they are trying to take away her independence.
On a side note, nephew said he discovered recently that she had never bothered to take the proceeds from his dad's life insurance when he died in 2004. He found out when someone notified him the state had over $100K in unclaimed funds in his mom's name - the insurance company had turned the money over to the state.