Some people get some assistance with devices through their LA, as mentioned above.
I think there are now likely cameras and security systems and things like those smart doorbells, that can connect to your phone, so you could monitor things remotely and see who is at the door and so on.
I hope you have PoA and already take care of the finances? If not, I'd say it's time.
I understand your worry. I found out after the fact, that my mother was not only giving out her credit card information over the phone to cold callers and so called "charities," but was also giving money and writing checks to people who knocked on the door. She even invited them in (she got a thank you note from a legitimate charity whose representative she apparently had in for coffee and a chat, and then wrote him a BIG check). She also got in car accidents and had a near miss with an electrical issue in her kitchen. I lost a lot of sleep, I can tell you.
So by the time my mother got to where she couldn't manage her finances and was giving money away to scammers, she also was at the point where she needed 24/7 supervision, as she was having other problems (wasn't eating or bathing or changing clothes or cleaning or washing clothes, wasn't taking medications properly and was over and underdosing on prescription and over the counter meds, wasn't sleeping, the list goes on). She ended up in hospital after being found wandering very early one cold morning, no coat, injured, hallucinating and disoriented. She was just lucky to have been found by a Good Samaritan rather than someone else. She went to hospital due to her confusion, dehydration, and to have her injuries assessed. She was malnourished and underweight and it was terrible.
I am sorry to digress about my own story. I think it sounds like your mother needs more help and support and I hope you will be able to get something in place quickly, to keep her safe, and for your peace of mind. Best wishes.