Good for her - it's nice to see kids interested in hunting
............ My daughter was 9 or 10 yrs old when she shot her first rabbit - she was so pleased with herself.
Personally, I'd go with an adult sized PCP - some of the junior rifles, like the Ultra JSR only produce 6ftlb.
And, I'd chose .177 for hunting as the pellets are faster and the trajectory is flatter at 12ftlb, giving easier accuracy.
The only other things I'd recommend is a bipod to help her with stability and, a bit of practice.
........... give me a shout when you've got your ri