I guess
@Koovie is talking about the fact there are numerous ongoing attacks in different locations across the country. It is a valid question and one the NSG (and others in India) are surely monitoring to learn what they could do in such a situation (standard procedure for the units, just like any units around the world factored in a Mumbai style attack into their preparations.
I have been following the French situation closely and many were saying that there was a fear the French elite units (RAID and GIGN) would be stretched too thin and wouldn't be able to cover a third or fourth scenario and this is perhaps what the terrorists were planning.
As such I would say that today the NSG is well prepared to deal with such a situation. Now of course it depends where the initial attack happens, in the post-26/11 scenario the closest NSG hub will respond with their ready team. If it is required the NSG's main CT task force in Delhi will also be flown into assist (they would already been on alert and awaiting the call). The NSG has depth in their units too, in Delhi and the hubs there are are secondary teams who would already be starting to prepare themselves for the eventuality of responding to a second, third, fourth etc situation.