I would like to know ERISA equivalent for a government organization in New York State
The New York Retirement and Social Security Law is the rough equivalent of the non-tax element of ERISA for New York State government employers (ERISA applies to private sector employers).
There are a variety of fiduciary duties under ERISA, however, and it isn't obvious from your question which duties are at issue. Some would be contained in the NYRSS like the laws governing how the funds are invested. Others would arise at common law, would arise from other statutes, or would be absent entirely.