The reason for choosing "a few" as the correct determiner is to provide context and clarify that the speaker ran back a short distance. "A few" is used to indicate an unspecified small number of yards, which is appropriate in this context, as it suggests a limited distance was covered when running back to where the figure had disappeared. The other determiners like "some," "the some," or "few" do not convey the same sense of a small, unspecified quantity.