Miss Honey is a grown-up and Matilda's a kid, but they've gone through very similar situations with very different reactions. Their family environments were unsupportive, to say the least. In Miss Honey's case, her childhood was physically abusive.
Miss Honey reacted by retreating, and Matilda reacts by fighting back. Miss Honey herself points out this important connection when she says, "'You must understand I was never a strong character like you. I was always shy and retiring'" (17.43). And Miss Honey may not even fully get just how strong Matilda is yet. Matilda's strong for Miss Honey when Miss Honey can't be strong for herself.
Miss Honey and the Trunchbull are set up as foils in quite a few ways. They both work at Crunchem Primary, and they're the two teachers we learn the most about. (Technically the Trunchbull's the Headmistress, but she teaches from time to time.) Where Miss Honey nurtures and supports students, the Trunchbull drags them down and criticizes them. Miss Honey teaches while the Trunchbull terrorizes.
Their treatment of Matilda highlights the distinctions between them. Miss Honey promptly realizes Matilda is amazing and wants to support her and help her brain grow. The Trunchbull seizes on the idea that Matilda's a troublemaker and accuses her of manufacturing stink bombs. If ever a pair were opposites, it's Miss Honey and the Trunchbull.
Mrs. Wormwood sets up the comparison of herself and Miss Honey by evaluating their life choices. She gives the example of beauty versus brains and claims beauty for herself, leaving brains for Miss Honey. Ironically, as the narrator points out, Miss Honey's got all the beauty and all the brains. Mrs. Wormwood is not smart, and she's not at all pleasant to look at either.
Finally, their positions as maternal figures link these two ladies. Mrs. Wormwood is the mother Matilda has, and Miss Honey seems like the mother Matilda wants. Mrs. Wormwood has many of the characteristics Matilda disrespects, while Miss Honey has characteristics Matilda honors. Miss Honey supports Matilda in the way that a mother should, and Mrs. Wormwood ignores her daughter in a way that no parent should.