The orbs are a side quest. You don't need to finish this quest to complete the main story quests. If you killed her AFTER the last time you slept at an inn, restore the auto-save game rather than the default save game. If you don't have a save game with her still alive, the orbs are useless. I can't remember if you can drop orbs onto the ground. If you cannot drop them, put them in a magical town hall vault or permanent storage chest.