Does any firms in India offer these kind of insurance?
No there are no firms that offer an individual insurance on default of such products. Partly the reason being that it is very difficult to understand the default, valuation of individual FD's in hundreds of companies. Arriving at right premium. Even if provided, it may be more than the interest rate that is offered. For example if you invest Rs 1 lacs in a non-rated Company deposit, that is offering 15%, i.e. Rs 15,000 as interest, the insurance cost can easily be around Rs 10,000. This means the effective return will be Rs 5,000 which is quite less than Bank Deposits and after taxes may actually be negative.
There are regulations in works that are now making it mandatory for companies issuing FD's to get an insurance if they default; there by securing the interests of the investor. This may take quite sometime as there are quite a few things that need to be sorted out.
Given this, it is advisable to only stick to AAA rated companies as in past quite a few companies have defaulted on Company Deposits.