Chu Yunli escorted the Ninth Prince back to the palace to report back to the Emperor. This was an order secretly given to him by the Emperor. The news was not made public and everything was done in secret.
Fortunately, the Ninth Prince was fine and was rescued safe and sound.
All this was thanks to Jiang Ning. If Jiang Ning hadn't discovered this a long time ago and took action to treat the Ninth Prince, the Ninth Prince would have been brutally murdered by now.