I'm not understanding what an alert system could do that a caregiver couldn't, in terms of contacting emergency services. And with ALS, there is really seldom an emergency that requires an ambulance, if the home has the proper equipment, such as BiPAP, suction machine, CoughAssist, hospital bed, wheelchair, Hoyer lift, etc. depending on her needs.
The reality is that as the disease progresses, it is less and less practical to have a "maid" [sic] without healthcare aptitude or experience care for your mom. If she is significantly cognitively impaired, it's really impractical now.
A home health aide (not sure what the levels are in Canada), nursing student, etc. would be more on point, and typically wages are not that high. In case of a genuine emergency, in particular, but also throughout the day, I'm sure you want someone who can help and interact with your mom the way she needs. So instead of looking at new systems, maybe you should look at a different support person.