It accepted my answer of "His wife must not wear any kind of dress." which has a very different connotation from the primary answer. Can the Esperanto sentence really be translated to either of those or does it tend to imply one over the other?
"his wife doesn't need to wear any kind of dress" (or "doesn't have to") = She may wear a dress (any kind) or not. (Maybe they are going to a casual party.)
"his wife mustn't wear any kind of dress" = She may not wear a dress (any kind). (Maybe they are going to play sports.)