I do have what is called a Knuckle Blaster (http://www.amazon.com/Knuckle-Blaster-Stun-Gun/dp/B008S8HCAC, but again, the crazies can ignore since it is lower voltage that a police style tazer, and you have to be up close and get wind up getting shocked yourself if not carefull.
As I mention above, ff you strongly grab a person by the adams apple, in my experience they quickly become docile. Krav Maga has many other pressure points. Yes, I know some incapacitate and others outright kill. I seriously don't care which in this day and my and my wife's age.
Don't have time to pull a gun (which I can't carry legally), or pull out pepper spray or a small hand held tazer. What do you do? I'm thinking throat grab; kick to the groin; step on their instep; bring your flatten hand upside their armpit, etc.
Also, check out Crossfit. Crossfit doesn't provide you a means of defense but it helps folks of all ages get fit and being fit is a major part of any self-defense program. Crossfit is particularly good for seniors...you will get VERY fit and love it (good for wives too).