Maybe simply

    CREATE FUNCTION [dbo].[fnct_rpt_ActiveHC_WithoutGrp_tarun1]
        (
        @adid1 varchar(25),
        @number int
        )
    RETURNS TABLE
    AS
    RETURN 	
        SELECT *
        FROM OD_SAP.dbo.ty_rpt_ActiveHC_WithoutGrp a
        JOIN [BI_Control].[dbo].[tbl_BI_AccessMatrix_ADIDcc] b ON a.CostCode = b.cc
        JOIN [BI_Control].[dbo].[tbl_BI_AccessMatrixMaster] C ON b.ADID = c.ADID AND C.IsActive = 1
        where @adid1 not in ('tachakr','BEULA','NI345519') 
           OR (b.ADID = @adid1 AND b.ReportID = @number)

?