I think that one of the most critical elements of Elie Wiesel's work is to probe the depths of what it means to "overcome" the actions of many during the Holocaust. There can be much to indicate that the notion of "overcoming" is complex, to say the least. This is not repudiating that there were individuals who were able to overcome what was done to them, but merely pointing out that there is an immense psychology that must be probed in this process. For example, Eliezer is one who "overcomes" through survival and endurance, but it is done at a tremendous cost. The loss of his faith in human beings and in his notion of spirituality, the loss of identity with both family and culture, and even the loss of a conception of life when he merely becomes a creature seeking to survive the brutality is something that the reader must confront. Certainly, there is a sense of overcoming with his survival. Yet, one cannot say that Eliezer, or anyone else from the narrative, overcomes it. The trauma and torment that has been inflicted becomes a permanent part of them, reason enough for the ending when Eliezer does not recognize who he is.
One of the problems with your thesis is the word "overcome" and its connection to the memoir Night and genocide. It would be almost impossible to demonstrate from Night that the Jews overcame genocide; in fact, Wiesel thoroughly discusses is struggle with losing his faith and recognizing his emotional death at the end of his Holocaust experience.
That being said, you could discuss how the Jews cope with the horrors of deportation and the concentration camps. Below are several examples of their coping:
1. Akiba Drumer, who becomes Elie's spiritual mentor in the camp, makes a point of trying to encourage others spiritually. He prays the traditional Jewish prayers and manages to maintain a hopeful gaze almost until his death. Even after his eyes have lost hope, he asks Elie and the others to remember to pray the death prayer for him, demonstrating that he still clings to his faith.
2. Many of the Jewish prisoners, including Elie's father, do their best to honor their traditional holidays. This demonstrates not only a longing to identify with better times in the past but also a hope that if they adhere to their religious customs, perhaps God will see fit to rescue them. Elie finds this practice extremely difficult. He resents his father for continuing the traditions and cannot bring himself to eat in celebration when he is supposed to.
3. The prisoners also cling to what remains of their family and friends. While the camps certainly encourage self-preservation over family commitment, Elie and his father seek to stay together. Even when Elie is frustrated with Chlomo's physical ineptitude, he still looks out for him. Similarly, when Elie first arrives in the camp, his distant relative Stein questions him about news from his family, hoping that they might have possibly survived.