Can you file for theft if someone who is not left as an heir takes off with something if they are not family? Part 2

First off I am sorry if this is getting annoying. My dad had a loan with his bank for the truck. He placed me as the beneficiary for the account. I am the only heir, his only child. His "Girl Friend" is holding his truck and was to trying and get money from me. The said bank forced me to pay off my fathers loan. So should I change the truck to my name? Today is day 40 and I would need to change it today. It's a matter of urgency. We are pretty sure she will take off with the truck. Can I file for theft IF I change it into my name? Yes we did ask for the truck repeatedly.