Why is the family so surprised to see Jess when he came back from the museum?

The family is surprised to see Jess return from the museum because they were not expecting him to come home so soon. His abrupt arrival catches them off guard, highlighting their lack of awareness about his whereabouts. Additionally, Jess's experiences at the museum may have changed him, creating a sense of curiOSity and concern among his family members about what he has encountered.