Q. An Avel that during the thirty days after the death of his mother leads the services at the Amud. does he have to do it next week, after all Chanuka is called a ‘Chag’?

A. On question 1222 regarding if Chanuka is called a Yom Tov or Chag, we wrote: “Horav Shlomo Miller’s Shlit’a opinion is that it is called a Chag and a Yom Tov as we find in Shulchan Aruch (Y. D. 217: 47) regarding a neder done exempting those days, that Chanuka and Purim are also considered Yomim Tovim at least in name. Taz (ibid. 38) explains that in the language and expressions that people commonly use, the are included.

Orchos Rabeinu mentions that Horav Chaim Kanievsky zt’l would indeed greet people with a “Gut Yom Tov” on Chanuka. See similar opinion in Alenu Leshabeach (6: p. 100).”

Mishna Berura (671: 44) mentions that an Avel that leads services on the first night of Chanuka he does not light the Menora in shul, since he would have to recite Shecheyanu, although at home he does recite that blessing.
He also mentions that he can lead the services yet abstains from the Halel recitation during Shacharis.
There are indeed different traditions about an Avel being a Shaliach Tzibur during Chanuka.

Horav Shlomo Miller’s Shlit’a opinion is that one should follow the tradition of the shul he attends.

Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a