Rewrite in your favorite modern language if you want to make something "better" (or "safer", or some other "-er")... but usually you end up with something worse because usually you don't have the years of trial-and-error, iteration, and refinement that most big name projects have.

Rewrite in C if you want to learn the underlying data structures, algorithms, and real-world computer science of the field. Database design is field with exceptional depth and many lessons to be learned.