Last Knight wrote, "Likewise, a dog - especially a large dog, like a pit or other 'guard dog' can be an unfair burden to put on an old lady. Dogs are expensive to care for, they require constant upkeep, and they can be something of a strain with the requirements of walks and playing and such like."
I completely disagree! With the possible exception of the OP, no one here has met the woman in question. No one knows what her physical and mental capabilities are. The only way a gun will be of any use to this woman is if she is able to get off the first shot (or shots) at her attacker.
Stopping your attacker means that your situational skills are honed to the point where you recognize the threat before it actually happens. Of course I don't know this woman either, but as people age, as a general rule, their senses become diminished. Three key elements of situational awareness are, hearing and seeing and reaction time, are these are usually the first to go.
My mother is 88 and without her hearing aids, she is deaf as a post. Even with them in, her hearing is only passable at best. There are numerous "bump in the night" posts here and making sure you come out on top is to hear the bump in the first place and react accordingly. If you can't even hear the bump, what's the use of having a gun?
Likewise, without her glasses, she might as well have her eyes closed.
As far as reaction time, this is usually the primary reason people in this age range lose (or should lose) their driving privileges.
Enter the professionally trained guard dog. I am not talking about some mutt rescued from a local shelter. I guarantee you that a well trained dog will have better hearing and vision than just about any 80 year old. Also, their reaction time is going to probably be better than a human being of any age.
Another advantage of a dog is that they will attack on command or when they sense their master is in danger. They are trained to react. They are animals and do not make any value or moral judgements regarding their actions. They will either stop the threat until they are called off or die trying.
A good agency will place the appropriate dog in the home for the situation at hand. Like hunting dogs, guard dogs are not necessarily pets. They have a job to do and love doing their job.
Scott