Miss Honey is Matilda's most important guide; she comes into the book at just the right time, and helps keep school from being just as much of a nightmare for Matilda as her home is. Miss Honey seems to realize exactly what Matilda's capable of, in terms of intelligence and learning, and decides to help the little girl at all costs.
Then, when all the antagonists try to keep her from helping Matilda, she only becomes even more determined to guide Matilda as much as she can, by giving the girl more advanced school work, becoming her friend, and eventually ensuring that Matilda can skip several grades and finally be challenged in school.
Mrs. Phelps plays the role of guide, too, although not as thoroughly as Miss Honey. Mainly, Mrs. Phelps helps launch Matilda's reading career by giving her a long list of awesome books to read. Plus, she even gives Matilda suggestions on how to read. We can't help thinking that without Mrs. Phelps, Matilda might never have been able to fuel her imagination and take down the Trunchbull. So in a way, you might say it all goes back to this unassuming librarian.