There is a tool called JL_Cmder that will do a complete wipe of the blackberry. This erases the operating system, applications, BES Security Policy, and data. Following this, you have to reload the operating system with the Blackberry Desktop software and a USB cable.
It goes without saying that the user should back up their stuff before continuing.
Securing the BB.
Once they the BB is running again, go to Settings -> Options -> Security -> General Settings. Set a real password on the device, enable content protection, set a security timeout, and enable prompt on Application Install.
In the firewall section, block MMS, PIN, and Enterprise Messaging, and enable the firewall. (Assuming she doesn't use those features.)
Option C. Buy the insurance on the phone and swap it out for another.