The late Robert Boatman, www.Boatmanbooks.com made the comment; Intimidation misses 100% of the time.
His meaning: a big scary gun is 100% worthless if you(or any family member/spouse) are unable or unwilling to use it.
I agree with taking her out to shoot or try a few brands, as noted too, only hits count. If the woman can use a medium frame DA revolver & shoot .38spl loads, fine. As she practices or trains, then she can move up to .38spl +P or even a .357magnum, then maybe buy a 9x19mm or .40S&W.
You don't need a 10ga shotgun or a .50BMG M-2 to defend yourself.
Carbines can do okay if the home owner desires a white light or laser system with a pistol caliber.
A 5.56mm - is a bit much IMO for most dwellings. A .38spl K frame or a .357magnum like a SP101 or 686+ with .38spl rounds can do fine to start.
How so?
Do we need to start yet another "5.56 for home defense" thread in general gun or rifles in order to discuss this (again)?