Rats are not native therefor are illegal to release.

Also think about he fact that snake keeper already suffer from a bad rep releasing a rat in the wild would only add to that.

Euthanize her and dispose of her or find someone locally (reptile store or snake owner) that can use he as a feeder.

Obviously this rat is/was a poor breeder (2 litters at age 2) is too old now anyway and is not pet material either since she bite so the best is to put her down a way or another.