Kaplan is right: 2 moles of gas (2H2) in the reactant side to one mole of gas (CH4) in the product side is a decrease in entropy. You dont even need to know the entropy values of these compounds.
Just to be clear, there is more than one value for the entropy of the compound depending upon the phase and whether or not solid carbon is present as diamond or graphite. Naturally, these are the values for gases and graphite.
I just think of it going from more moles of gas to less moles of g should be a decrease in entropy. 2 mole of gas is 2x(number of atoms in 1 mole of any substance). Twice as many atoms means more bumping around and more disorder. Sorry for the simple explanation. Its how I would have answered the question.