What is the next step to be done from H1B to finally go to India for GC.
Answer: You wife needs to apply for green card to start with which involves:
1. Labor certification which can take from 1 month to 2 years depending on where and how it is filed. Check Labor Certification thread for details
2. After 1 is complete and approved, file I-140 with CP option. I-140 clearance can again take anywhere from 2 months to 14 months depending on where and what category itis filed under and assuming there is no RFE (Request for Evidence). Check I-140 for your service center (which can be CSC, TSC, VSC, NSC)thread for details
3. After 2 is approved, it takes about 6-8 months to get CP interview. Check this thread (consualr processing) for details