Dear Amit,
It's true that there is not enough information on Grievance handling. This is one of the processes in HR that requires your own neutrality and judgmental approach while dealing with any kind of issues or grievances. This activity requires HR professionals' intellect and empathy to deal with. There is no specific questionnaire that can be made as it totally depends on the kind of grievance the employee is facing.
First of all, try to understand what made the employee feel aggrieved - is it related to any policy, misconduct, or harassment? There can be numerous reasons. Then, try to address them accordingly. If it is a policy issue, try to gather their suggestions for improvement, conduct one-on-one sessions to better understand frequent comments and feedback, and then make decisions to enhance the situation.
If it involves misconduct or harassment against a particular employee, then you need to follow a different procedure which begins with a written complaint, a charge sheet, a show-cause notice, and then reaching a common judgment of suspension, termination, withholding salary, etc.
Please let me know if you need any further information on Grievance handling!