Answer:
Their belongings, their lives, the idea that they're going to a resettlement camp.
Step-by-step explanation:
They're forced to leave all of their belongings on the wagon, which they packed because they believed they were going to a resettlement camp, but when they realize they're going to a concentration camp and are forced to leave everything behind, they see the reality of their situation and it symbolizes the end of happiness, family, home, warmth, food, life (for many), safety, freedom, and innocent optimism.