JohnKSa, we have to disagree on this one.
If I hear something downstairs that sounds like a threat, and I know my mother is down there, then staying upstairs and guarding the landing becomes my wife's job. (She has a gun of her own.)
Unfortunately, due to bad knees, etc, there will not be any way to consolidate all loved ones in one part of the house. (My mother and my wife's father have a very hard time with stairs.)
This is a fairly common problem, and one that people might want to consider when laying out their homes.