Let's all forget caliber for a moment. We are going thru a situation similar to yours. If she is comfortable with a 22, go with it. Try to move up gradually. Even a bad 22 is better than a great plan on paper and no protection.
Why do I feel like this? I have a friend with the same RA as you talk about. She has used a 22. She is comfortable with that rather than nothing.
I like a 9mm. I certainly would not stand in front of someone with a 22 and let them fire while I tell them how ineffective it is. I do understand certain calibers are better. I just think given a certain situation anything is better than nothing.
My 2 cents. It is worth what I charged you for it and no more. It is your decision. Best of Luck.