According to another article, the bear ambushed her, and she would not have had time to react and fire on the bear.
I read the coroner's report. It says the bear likely ambushed them, and was hidden two meters off the trail.
It does not say how far from the mother and child it was when it started the charge.
I could have been six feet, it could have been 50 feet.
Historically there has been more than few that have managed to draw a pistol and stop a in progress attack by a brown bear.
We will never know the answer in this case; but we do know that without a pistol she had no chance.
The best plan(if you must) is to travel in armed pairs of humans with at least a 15’ gap.
Walking through the forest looking at their iPhones?