Actress Eliza Dushku and her mother, Suffolk University government professor Judith Dushku — or, as Eliza calls her, “Momma Judy’’ — were at Brandeis this week talking about THRIVEGulu, their nonprofit organization focused on building and operating a trauma-healing center in Gulu, in northern Uganda. The mom-and-daughter duo were the keynote speakers at ’DEIS Impact, Brandeis’s annual festival of social justice. Dushku was introduced by her former Sunday School teacher, Marci McPhee, who’s now the associate director of Brandeis’s International Center for Ethics, Justice, and Public Life. The “Buffy the Vampire Slayer’’ actress drew laughs from the crowd when she copped to being something of a “punk’’ in McPhee’s class. (Give her a break — she was only 12.) Afterward, Dushku and mom happily hung around to talk to students and pose for photos.