Let me propose a slightly different programme.

Lufthansa: SFO-FRA-BOM. You will arrive in BOM early morning at around 1:30 am. Take the first Jet Airways BOM-BLR flight. For the return, simply retrace the above flight path.

The advantages of the above are, Lufthansa provides one of the quickest getaways to India from SFO. The transit in FRA is less than 2 hours. By contrast flying economy on the Singapore route can be a very long and tiresome proposition. The SFO to Hong Kong segment, especially, is interminably long (one is better off going via Seoul, bypassing Hong Kong).