Pat is so correct on this. And everyone here will tell you that her advice is not only right, it's important that you get your grandmother to do as she suggests. Whether she feels like it or not.
I know that she's an adult and can make her own decisions, but she's making the wrong one here. Perhaps you can talk with the urologist and have him suggest going to a larger facility with a higher volume of BC surgeries. My own urologist was gracious enough to suggest to us that we go to USC/Norris, and that while he could do the surgery, he did only one or two a year.
Do whatever it takes. If you're successful, terrific. If not, well, you tried.
(In the interest of full disclosure, my own grandmother was from Scotland, and pretty stubborn, too. I don't know if I could have convinced her to do something if she'd made up her mind no to.)
Good luck,
Zach