I would look into getting and wearing an Apple Watch. It can detect falls and will call Emergency Services automatically. Plus, if you fall, you may not be able to reach your phone. I don't know if other watch brands can do this. There may be some that do and are less expensive. Apple Watch, though, is MUCH less expensive than a service like Life Alert.

Also, the odds of you being injured by something as simple as a slip and fall are hundreds of times higher than someone coming into your home to harm you. Make sure you don't have any slippery area rugs or things like that. Make sure all the lights in your home are bright enough for you to see well.

Finally, is there someone--a friend or relative or maybe a local senior center--that you can ask to call you once a day to check on you? You could set two times. If you don't answer the first time because, perhaps, you're taking a nap or don't hear the phone, they would call you at the second time and only then if you didn't answer would they send someone to do a wellness check.