I think the correct order from most entropy to least entropy is C2H4, N2, and H2. My reasoning is that C2H4 has the biggest number of microstates which means that it will have the most entropy since it. I then based N2 and H2 from there weights (which indicates size) since the larger something is the more microstates it is likely to have.
I hope that helps. Let me know if anything is unclear or if you want me to add more detail.