Generic : Is 222 or 246 a good NMAT score?

Yes, both 222 and 246 are good NMAT scores. As per GMAC's percentile table, a total score of 222 is at the 92nd percentile, and 246 falls in the 245–360 band, which is the 100th percentile. Compare your target with the NMAT cut-offs of the colleges you plan to apply to.