One thing is not clear at this time. What is the purpose of visiting the USA? Whatever the reason is but in general here are the list that my parents have submitted to receive a visa.
1. Relation certificate
2. Bank balance
3. Property evaluation
4. Sponsor letter from your side
5. Employers letter if your parent still have job.
6. Your pay check if you are sponsor
7. Police report and health report are optional(We didn't submit)
8. Invitation letter and mention clearly why you are inviting your parents.

I hope this will help you.