In addition to our learned members' reply on insurance policies, Employees' Compensation Policy is statutory in the absence of ESIC Statute. Hence, you need to take EC Policy with any private insurance companies available at your location.
The other two policies, GMC Policy and GPA Policy, are only optional. But these policies will give a name in the industry that your company has welfare aspects, which will give you an edge over other companies. Though the amount spent on these policies is small compared to other welfare expenses like canteen and transport, these policies will add value to an organization's ethics in line with multinational companies.
In some companies, they are going an extra mile with an addition of a wonderful policy called Group Term Life Insurance Policy with LIC. In the event of the unfortunate death of an employee, the nominee will be paid a hefty sum, which not only supports the family but also builds trust in the company.