You can apply for the visa in either Kochi or Bangalore for the Karnataka & Kerala visa region. Regardless of your citizenship (unless you are an EU citizen, then you don't need a visa) you have to apply in the country of your residence (work or studies), so you need to apply in India (and in Kochi or Bangalore since that is where your regional offices are).
There are a list of documents required for Visiting Family & Friends in Germany which you can see here.
You would require the following, please see this list for the required documents:
- Proof of accommodation for your entire stay in the Schengen area
- Proof of sufficient funds for the visit:
- If sponsored: Verpflichtungserklärung (formal obligation letter) of your sponsor
- Proof of civil status: Marriage certificate, birth certificate of children, death certificate of spouse, ration card if applicable
It may also help to provide more information:
- His bank statements (seems like last 3 months should be sufficient, but last 6 months won't hurt)
- Proof of his employment
- Proof of you being a student
Also the German Embassy or Consulate may require additional documentation, that is not on their list of required documents.
There is an unofficial list of the additional documentation. Also there is a unofficial list of the proof of subsistence required for Germany.