I will just throw this out there as an option...
During my days of school I worked at a Pawn Shop on the weekends...she could pawn the gun for a low dollar amount and it would essentially be a low cost safe storage. An example, if she came in and pawned it for $20, it would cost her $23 to pick it up within 30 days, $26 bucks for 60 days, and $29 bucks for a 90 day loan...the longest you can have a loan out is 90 days without coming in and paying the interest off on it. College Station Pawn is Aggie Owned and operated (at least it was when I worked there). He is a good Ag, he would routinely buy "lost" Aggie rings and return them to the ring office to be returned to the owner on his own dime. (Unless he saw the same ring more than once, then he would just assume they were selling their ring and didn't deserve it.) Anyway, upon request, they will put a note in the system to call someone if the gun has been forgotten about and no interest paid on it before they pull the gun assuming no one is coming back for the gun. If she did the loan for $10, I think it would basically turn into a $2/ month storage. Another plus is that Champion Firearms with an indoor shooting range is literally less than a mile from the pawn shop and less than 3 miles from campus, so it would be convenient as well, and they are open 7 days a week so it shouldn't be a problem finding time to get the gun when she will need it.