One hit from a 1911 would have been better.
Of course, a single hit from anything is better than 30 misses. However is there any information about how many times the murderer was hit? If trying to keep him pinned down, the more the merrier, when it comes to shots fired. Though the use of "covering fire" isn't a good doctrine to be using in a civilian area.
But I agree, a more potent round would have been better. But if that's the round she's most comfortable with then that's what she should be using. The Bererra is a relatively large and heavy handgun for a 9mm, making it relatively easy to shoot (though some women and men with smaller hands dislike the wide double stack mag well grip).
My choice would be my Glock 31C, with 15 rounds of 357 SIG on tap.
This vest thing has got me thinking though. Might not a 357 revolver loaded alternately with 125gr SJHP and 180gr hardcast be a winner?