Sorry to her she was bitten. Hope she's OK.
I never understood shooting snakes. Except in water, swamp, or a tree, a handy stick or branch is enough. In the yard a hoe or shovel will end things swiftly. And, I don't have to explain gunshots, nor clean the gun. Seems like an excuse to just use the gun to me, but I also recognize there may be more to it than what I can think up.