There were NO Russian young women of equal Noble rank to Nicholas Alexanrovich, other than his immediate cousins. The rules were quite strict about the Emperor's wife being of equal birth.
From the "Statesman's Handbook" 1896, printed by the Russian Imperial court:
Thus the principal condition of belonging to the Imperial House is lawful marriage. In order to be lawful these marriages require the observance of certain special conditions, different from those set down for ordinary subjects. Namely it is indispensable, firstly, to have the sanction of the reigning Emperor; secondly, that the persons about to be married should be equally high born and thirdly, a person of the male sex, with the possible right of succeeding to the throne may marry a person of another faith, only on condition that she embrace the orthodox faith.