A previous answer says that 3 female characters are mentionned in The Hobbit :

 - Belladonna, Bilbo's mother 
 - the mother and Fili and Kili
 - Wife of Girion of Dale

I can add :

 - 2 sisters of Belladonna, as she is is mentionned as one of the 3 Old
   Took's daughters
 - Gollum's grandmother. In the chapter Riddles in the dark : "Gollum
   brought up memories of ages and ages and ages before, when he lived
   with his grandmother in a hole in a bank by a river", and slighty
   later : "Gollum remembered thieving from nests long ago, and sitting
   under the river bank teaching his grandmother, teaching his
   grandmother to suck - "Eggses!" he hissed."

There are also females refered to, in the plural : 

 - First chapter, we konw that there are hobbt girls as well as boys
   "[Gandalf] had been away over The Hill and across The Water on
   business of his own since they were all small hobbit-boys and
   hobbit-girls."
 - Smaug is said to devour inhabitants of Dale, especially young women
   "Later he used to crawl out of the great gate and come by night to
   Dale, and carry away people, especially maidens, to eat, until Dale
   was ruined"
 - and last, when inhabitants of the city of the lake flee form the
   fire, "women and children" get into the boats.

So, though there are no female roles, we at least get to know that hobbits and men have daughters and wives. As for elves, there is no mention of females ever ; and for dwarf, the sole mention of the mother of Fili and Kili is very short. Yet, it doesn't say that there aren't females elves and dwarves, it's just that they aren't specifically mentionned.

Quite often, we think that there are female characters in the hobbit, because they are in The Lord of the rings, like female elves, female hobbits, and we mix the two stories in our memory. But in The Hobbit, the terms stay in the genre-undetermined plural : the elves, the hobbits, the Sackville-Bagginses. As an example, il the last chapter, the Sackville-Bagginses are suspected of stealing the silver spoons but it's "they". No mention of Lobelia in The hobbit ; she appears only in The Lord of The rings.