So can a pump 12-gauge shotgun. But seriously, as one earlier poster mentioned, I'd be more worried about elderly parents falling, or having a stroke or other medical emergency. There are a number of small devices that people wear around their neck and when they have an emergency, pushing a single button calls 911. They are much cheaper than a full-blown security system.
I've had four monitered security systems in varioius houses I've owned over the years, and have concluded they are a waste of money and more nuisance than they are worth. In more than 30 years of having a monitored system, we never, not even once, had a real alarm. All were accidental (and a lot of them when the kids were still at home). Where I live now, police, fire, or emergency services response time would be 45 minutes or more so a security system would be essentially useless. I do, by the way, have a pump 12-gauge shotgun, as well as several other weapons within easy reach. The wife knows how to use them all, and quite well.