One theory has Quincey referring to the Parable of the Ten Virgins in Matthew 25:
Then shall the kingdom of heaven be likened unto ten virgins, which took their lamps, and went forth to meet the bridegroom. And five of them were wise, and five were foolish. They that were foolish took their lamps, and took no oil with them: But the wise took oil in their vessels with their lamps.
Except that, of course, he's got the number of women wrong - it should be either five or ten. Some argue that Stoker is deliberately painting Quincey as an ignorant American. Or possibly he is conflating the Matthew lamp parable with this prophecy from Isaiah 4:1, implying a scarcity of bridegrooms for women who wait too long:
And in that day seven women shall take hold of one man, saying, We will eat our own bread, and wear our own apparel: only let us be called by thy name, to take away our reproach.
An alternative theory is that the seven women with lamps are the Pleiades of Greek mythology, the seven daughters of Atlas. When Atlas was forced to carry the Heavens on his shoulders, he left his daughters vulnerable to the unwelcome attentions of the huntsman Orion. To save them, Zeus turned them into stars (lamps?). Orion will forever pursue them across the night sky - the ultimate runaway brides.