dear Miss(y), dear girl (literally) young lady (humorous) Fräulein is a dated expression almost exclusively used when adressing (in a rather condescending manner) or scolding a little girl nowadays....
There is no opposite for Fräulein. Fräulein ment a lady which wasn´t married. For man there is usually Herr, if they are married or not. Nowadays you don´t use Fräulein anymore.