There are not many examples of true trust and friendship in Night by Elie Wiesel--and we understand why. This setting and these circumstances are not in the least conducive to fostering trust or maintaining friendships; on the contrary, everything that happens creates distrust and discourages friendships.
True friendship and loyalty is seen, however, before the Wiesels leave Sighet. Their long-time maid, Marta, is no a Jew but is willing to help the family get to her relatives' home where they can hide until the storm of war passes. This has two levels of friendship, as Marta not only wants them to be safe but she is willing to make a sacrifice for them to do so; families caught harboring Jews were also killed during this Holocaust, so this offer demonstrates an extreme level of her trust and friendship They do not accept her offer, but that is not because they do not trust her. Another friend is the Hungarian police inspector who comes to the ghetto and tries to warn Elie's father to escape. His effort, motivated by friendship, is unsuccessful, but he tried. Moshe the Beadle also displays true loyalty and friendship to his fellow Jews by trying to warn them about the horrors to come, though no one believes his story.
Once they Jews are forced into the ghettos and then onto the trains, everything changes. Friendship and loyalty are higher-level emotions, and they cannot compete with the basic instinct of survival; eventually there is little else which motivates them.
At first there is family trust and the friendship of fellow Jews sharing an awful circumstance, but the fellow-Jew attitude stops even before they arrive at Auschwitz--and we see it happen. Madame Schachter's rants are ignored by everyone on the train for a while, but soon her fellow passengers can take no more of her horrible cries and try to subdue and restrain her by degrees; finally they resort to knocking her out just to have some peace.
Once they arrive at the camp, the prisoners who greet them taunt and scare the new arrivals, their fellow Jews. There is no loyalty or friendship in this place other than in the family connections of the most recent prisoners. We see Elie's father sacrifice himself several times for his son, and when he thinks he is dying he leaves Elie his eating utensils, the only inheritance he has to leave to his son.
Even those family relationship begin to dissolve over time, however, and soon Elie admits this, after a guard hits his father:
I did not move. What had happened to me? My father had just been struck, before my very eyes, and I had not flicked an eyelid.
And we know that Elie is tempted to ditch his father during their long trek in the snow. If the love and trust are gone between a father and son, it is not likely to be found among strangers. By dehumanizing the Jews, the soldiers effectively eliminated any sense of trust or loyalty; the only thing that matters to any of the prisoners eventually is, of course, survival.
We do see some moments of kindness, which might be considered an incipient form of friendship. Alphonse does what he can to get more food for those who are weak, and Juliek offers hope to others in the form of his violin. Meir Katz saves Eli from being strangled and Yossi is a kind of friend to Elie. These are moments of friendship amid the overwhelming landscape of distrust and despair. The desperate quest for survival does not generally leave any time or energy for trust and friendship.