This excellent 22-minute MUST WATCH video by "Senior Safety Advice" describes many signs that a senior parent should start considering a safer living environment. Senior Safety Advice is a website by Esther Kane and Robin Schiltz.
From the video intro: "The chances of one of your parents ending up living alone are fairly high. But that doesn’t mean that they can or should be on their own. Senior Safety Advice has created a video of the top 10 signs to watch for that could indicate whether it is time to consider a new living arrangement for your elderly parent."