How do you know when it's time for your loved one to go into a facility?

My MIL has mild/moderate Alzheimer's and lives alone. She is still able to do ADLs but can no longer manage her meds, finances and had her keys taken away last year. She will wear the same clothes for a few days and doesn't bathe nearly as often as she used to. If she knows she's going somewhere, like the doctor, she bathes. My nephew took her out of town one weekend and said he saw her doing some things that concerned him and he doesn't believe she is safe to live on her own. He didn't say what she was doing though. He just said that he's surprised that she hasn't hurt herself or worse. She has told me about some hallucinations that she's had and she has strange dreams. She doesn't seem necessarily scared over it, but more like scratching her head wondering what is going on. She's still lucid, but has the normal cognitive and memory issues that come with AD. At what point is it time to think about trying to get her in some sort of facility? She's also very stubborn, determined that she is not going into a NH. She holds the belief that family should take care of her personally no matter what and if someone is put into a facility that means that their family just doesn't want to fool with that person anymore. So we have that to deal with too. Do we just have to wait until she hurts herself and has no choice but to go somewhere? Moving in with us is not an option. I look after her the best I can but I have two small children to think about, plus there is just not enough room. What can we do or is there anything?