And if the husband and wife with their dog had a gun do you really think that they could have defended themselves? Trained law enforcement officers know better than to engage in a gunfight when someone had the drop on them. Most of the deaths by handguns are suicides and people shot by a spouse or friend or playmate by accident.
Guns give people a false sense of security and if you shoot someone in most states regardless of the circumstances you will spend the rest of your money and much of your life in the courts. Only law enforcement officers get to shoot people with impunity.
For a single woman a large male dog like a German shepard or a Rottweiler will have a protector and a companion.
The idea of being protected by a gun and being able to survive a shootout is a very American male fantasy promoted by Hollywood and the NRA and the gun manufacturers. Good for corporate profits but not at all good for society as a whole - should anyone really care anymore.