No, she doesn't. Hannah is from the future. She knows what the Nazis are planning to do to the Jews. She doesn't believe their explanation about why they want the villagers to get on the truck.
The answer to your question can be found in chapter nine of The Devil’s Arithmetic. No, Hannah does not believe the Nazi soldiers when they show up at the Jewish synagogue and announce that the people attending the wedding are going to be relocated due to a new, benign government policy. Specifically, the Nazis say, “anyone who wants to work will be treated humanely.” They are promised good care and happiness among their own Jewish people. Hannah, finally aware of what time period she has entered, announces to everyone the general horrors of the Holocaust: the Nazis will place Jewish people in concentration camps and kill them in gas chambers and ovens. No one believes Hannah. In fact, Gitl is forced to defend Hannah by saying that she has just recovered from a sickness that has affected her mind. Gitl says that the illness caused “too much imagination and stories filling her head.” The crowd compares Hannah's ideas to the tale of Hansel and Gretel (during which an evil woman tries to throw the two children into a hot oven) and convinces everyone that Hannah’s suggestions are just child’s play and stories.
The ascent of the villagers into the awaiting truck was for their safety, explained a Nazi colonel to Rabbi Boruch, Shmuel, and another man who is unknown to Hannah. Hannah does not believe the Nazi’s explanation; whereas, the villagers are appeased by this explanation and quickly board the trucks.
Hannah, aged twelve, is a fictional character in the novel, The Devil’s Arithmetic, who has been transported back to the time of her Jewish ancestors. Therefore, when Hannah notices the men attired in uniforms alongside military vehicle; she immediately identifies them as Nazis and distrusts their given explanation. This is because she is aware of the historical past of her Jewish ancestors and the intentions of Nazis towards the Jews, and this knowledge makes her apprehensive to the actions of the Nazis.
‘And then, all of a sudden, she knew. She knew beyond any doubt where she was. She was not Hannah Stern of New Rochelle, at least not anymore, though she still had Hannah's memories. Those memories, at least, might serve as a warning.’