We know that there was no longer prophecy at the period of the story of Chanuka. As a result, the story of Chanuka was unable to be written in a way deserving an inclusion in Tanach. This was because there was no one with the level of Ruach Hakodesh required to author a sefer of Tanach. So Megilas Antiyoches is not in the 24 books of Tanach. R' Yosef Chaim Zonnenfeld teaches that the date of Chanuka, the 25th of Kislev, alludes to the fact that the first 24 books of Tanach can be written down, but not a 25th. The name חנוכה is a contraction of חנו כ"ה, meaning we must stop (חנו means to rest, stop) writing before including a 25th book (כ"ה has a gematria of 25).
The Midrash writes that the 24 books of Tanach correspond to the 24 mishmaros, the Kohanic and Levite families who took turns performing the avoda in the Beis Hamikdash. This is because the 24 books of Tanach are shamur, guarded. They are protected and one isn’t permitted to add to them. In this context we can understand the name חנוכה as חנו, they rested, כה, when they reached the 25th.
R' Yosef Chaim Zonnenfeld tells us an allusion found in the word חנוכה. It is an acronym for ח' נביאים, ו' כתובים, ה' מגלות, eight books of the Neviim, six books of Kesuvim and the five of Megillos. These are the only sefarim to be included in the Torah.
