I just finished watching Empresses in the Palace on Netflix and wondered about the harem after the emperor's death. This topic might be discussed in the longer original series, but I'm only a couple episodes in there and I don't know how accurate what they say would be, anyway.
So, historically speaking, during the Qing Dynasty, what happend to an emperor's harem (from empress all the way to female attendants), when an emperor died? I assume depending on their status (rank, children or not, maybe other things), the results for them were different, but what could they expect to happen to them?
I can't be sure this information applies to the system as it was under the Qing, but during the Tang dynasty an emperor's concubines would have their heads shaved and be required to retire to a nunnery after the emperor's death. This was because it would have been an insult to the dead ruler's memory for the women to have relations with another man.
We know that his was the fate of Wu Zetian in the seventh century. She had entered the palace as a concubine of the Taizong emperor, but was retrieved from her nunnery on the orders of his successor Gaozong, whose concubine and, eventually, successor as ruler she became. This was an apparently unique reversal of the usual custom and caused significant scandal in Wu's time.
I wrote about Wu and her life and times, including her consignment to a nunnery, in much more detail here.