The primary obligation of Shabbat candle lighting rests upon the "Akeret Ha’bayit," the woman who runs the household. Under normal circumstances, this would be the wife/mother, and her lighting fulfills the obligation for all members of the household. Therefore, the prevalent practice is that the unmarried daughters living in the home do not light Shabbat candles, and instead rely on the mother’s lighting. An unmarried girl who insists on lighting should certainly not recite a Beracha. But in any event, it is proper for them to follow the common custom and rely on their mother’s lighting, rather than light themselves.
Unmarried yeshiva students living in a dormitory or apartment away from home are required to light Shabbat candles, with the Beracha. One student should light the Shabbat candles, through which all the others living in the apartment or dormitory fulfill their obligation. If they wish, they can establish a rotation system whereby each Shabbat somebody else has a turn to light Shabbat candles on behalf of everyone in the apartment or dormitory.