@Rajneesh
Immediately after leaving these two contributory employees, ( return due in next month) just intimate the RO/SRO of ESIC the situation, as there is no contributory employee present in establishment within range of 1-21000, so the establishment would not e in position to file monthly contribution, and will resume to file again if the establishment appoint any employee within the contribution range i.e below 21000/-
keep the stamped acknowledgement in records for safeguard during any surprise visit or SCN by ESIC