If you are creating a retirement corpus than I would go for ELSS. Because you can review it after 3 years and move to other ELSS or other investments, if not performing and more chances that it will give you more return than other instrument suggested by you -
ELSS - Lock in for 3 years.
PPF - Lock in for 15 years.
NSC - Lock for six years.But all interest income is taxable at the respective slab rate of the individual.
Bank FD - Lock in for 5 years. Taxable


Note - The above instruments you can use for risk diversification.