When they returned home after talking with the trolls, Elsa locked herself in her room. The king and queen decided to leave her be for a while, to let her deal with the guilt of hurting Anna. When the servants came in to bring her food, they often found her sitting on the floor, unmoving and not responding to queries about her health. On those occasions, they set the food near her and left. Eventually, they stopped asking. It took a month before they realized that recently, she hadn't been responding not because she didn't want to talk to them, but because she was dead. The rats had been eating her meals.