There are 1.6 million Jewish people in NYC which has a total population somewhere between 8 and 9 million people in total.

Technically speaking, nobody ever needs to meet with any minority groups. But if you're trying to win an election for public office, it's probably a good idea to do so if that minority group is significant enough in size. Like looking at your list, I would say that someone should meet with an Indian organization (200,000+ in NYC), but probably not a Guatemalan (70k in the whole state), Mongolian, or Cambodian (can't find population figures for those groups) organization. In lieu of a Guatemalan, Mongolian, or Cambodian organization, they should meet with a Hispanic/Latino or Asian organization.