screen mesh 156 or 280 for this one

My suggestion most often is to go with the coarsest mesh count you can get by with especially if you're not very comfortable and consistent with burning halftones and using higher mesh counts.

The image is hard to see and it didn't enlarge when I clicked on it.

I'd opt for the 156. But either way you should work on getting proper exposure which starts with the art, screen prep, emulsion type, coating technique and light source and how you go about determining your times.

I'm nuts, so pay no attention to me, but if the black is solid, I'd go for a 156 on the black and high 2's for the 2 colors.
Another option would be a 195 to make the black closer in look to the two colors and not be perhaps "overbearing".
Whatever you use, good emulsion and a good burn will be needed as pointed out by a previous poster.