Premise: "A small girl is wearing a costume and a festive hat and looking thoughtful."
Hypothesis: "A girl is wearing a costume for halloween."
Do we know that the hypothesis entailed by the premise? Now, let's be accurate as possible. Some thinking first:
A small girl is wearing a costume and a festive hat and looking thoughtful does not necessary that she is wearing a costume for Halloween. So, the answer is it is not possible to tell.