Have you been sitting with her? If not, I'd go sit with her, and the next time walk her through it, make her take her time. Practice squeezing off on the deer with the safety on. then take it off and have her repeat.
Maybe try running her around in circles at the range, until she is out of breath, then telling her to sit down, and giving her 10 seconds to make a shot. Repeat until she is comfortable.
I know a lot of people that have the tendencies to throw the gun up and start blasting, as soon as they see a deer. Heck, I'm one of those people.
