45 wouldn’t have made any difference. The difference on the street is utterly negligible, and in any case, she would have missed those first several shots and run empty.. then she would have been in reload mode. Also she was moving backwards as she shot. When he presented the threat, time to lock up and use that front sight.
Years ago, when the army was pushing 9mm as the new "Personal Defense Weapon (PDW)"(army civilian speak for "Pistol") caliber, I was a smart youngish Marine captain and I asked the army colonel giving the presentation if this was the "same 9mm caliber that the Germans lost two wars in a row with".
He said "shut up and sit down".