You can't apply for a group tourist visa, you need to apply for individual tourist visa for them, each one should give your below documents, then you can apply for a tourist visa for them at the CVASC in New Delhi or Mumbai:
1. Application form
2. applicant's passport and One Passport photocopy.
3. One recent passport size photograph.
4. Covering letter from applicant's company or employer addressed to the visa office, if the document is not available, proof of travel expenses is required.
5. Photocopy of a confirmed return air ticket
6. if your friends are not Indian, the valid Indian visas or valid Residence Permits in India are also required.