Dear Bijay,
Employees will Hop, even with the best of the references and verification. Therefore you will have to enagage the employees, make the culture more robust and liberal. The culture should be based on openness and not on not rules & regulations. Rules and Regulations are a part of the culture and not the culture. Therefore, employee engagement, Openness in the company, will help you to retain them.
If many employees are resigning, than check the actual reason for the exits, you may be also surprised with the real reason. Try and eradicate that reason, so that more stability is pulled in.
Regards,
Ashutosh Thakre