Q is for Questions

In Norse Mythology the way to wisdom (which to the Aesir is worth more than gold) is by sacrifice, hardship and seeking. Asking questions of the dead or the wise was one way to find wisdom.

When Odin traveled to Hel, land of the dead, he conjured up the ghost of a dead seeress (clairvoyant witch).
He began to ask questions in order to find out the fate of the troubled Baldur, the most beloved god in Asgard.

"Who has forced me above ground and awakened me from my death?"
"Vegtam the Wanderer. Why is Hel adorned in gold?"
"For Baldur the bright.Now I must go."
"No. You must tell me, who will slay Baldur?"
"His blind brother Hod. Now I must go."
"No. You must say, who will avenge his death?"
"Vali will be one night old when he carries Baldur's killer to the pyre."
"Who are the maidens who toss their scarves to the sky?"
"You are not Vegtam. You are Odin, old as time."
"You are a liar. You are not a seeress. You are the mother of three monsters."

As I understand it, the correct question is as important as the wisdom contained in the answer.
Who is the mother of 3 monsters?