How do I know which home alert system to get for my mother?

One suggestion is to call local care agencies, or even your hospital, and ask if they have suggestions for reliable companies. Word of mouth and personal recommendations are best. If you know others caring for elders (in your area), ask them what they think. Nosing around locally may get you to a place where you are comfortable. One thing to watch - you shouldn't have to sign a contract for a specific length of time. What if your MIL suddenly needs to go to a nursing home? You don't want to be stuck paying off a contract.

That said, these alarms are great. I've used them for several of my elders.
Carol