No. Probably worse for range - slightly.
B is intended for the times when engine braking is needed, such as going down a significant hill. It's just more aggressive in its use of regeneration - taking power off the motor to charge the battery - than D. Regeneration is roughly 3/4 efficient, much better than friction braking (0% energy recovered for re-use), but not nearly as good as not needing to slow down at all (100% kinetic energy still in use).
If you are doing lots of stop-start driving in medium speed traffic, B mode might be more efficient, by providing a smooth and even slowing effect so that you use the friction brakes less than the same traffic conditions but in D. Otherwise, though, B mode wastes a bit of energy whenever it slows you down a little more than you needed.
Regenerative braking is great, but it's not a completely free lunch. Definitely more energy-efficient to brake less in the first place.
