Who is Lou Stone from The Water Is Wide and what is their importance?

Lou Stone is Ted Stone's wife who works as the island postmaster and school bus driver. "A lover of flowers and solitude, she seemed perfectly adapted to the Spartan existence on Yamacraw. She drove the school bus as proudly and as competently as Junior Johnson drives his stock cars. She delivered mail daily, depending upon the weather and her mood." Chapter 4, Page 76