To try and make it as real as possible, I’d give her a common MN rather than something fanciful. As for surnames, I’m rubbish when it comes to those, so maybe you could think of her heritage and what her surname would be, and use the surnames board and database for help, it’s like this database but for surnames which is really helpful!
Miranda Kate
Miranda Alice
Miranda Lee
Miranda Jane
Miranda Jean
Miranda Julia
Miranda Marie
Miranda Lynn
Miranda Elizabeth
Miranda Rachel
Miranda Katherine
Miranda Michelle
Miranda Megan
Miranda Claire
Miranda Faith
Miranda Hope
Miranda Christine
Miranda Louise
Miranda Nicole
Like any? Good luck with your novella :)