I love
Prudence. I love that it's a rather ugly sound, but looks beautiful written out. Most people upon hearing it would be like "Eugh,
Prudence?!" behind her back, but she'd know she has the coolest name on the block.
The song and Farrow aside, I'm a fan of most virtue names. My love for
Pleasance only surpasses
Prudence.
I'd go with
Pru as a nickname (although I do work for an insurance company and
Pru is what we call Prudential, but most people won't have that association).