Group communication applications, in general depends on the specifications you choose. Here, in particular if you go for EGC applications, it is also important to consider the timing analysis. You may go through our article of " Throughput and delay monitoring of MANET routing Protocols" for ZRP and its variation in TPT and EED analysis.
What Kind of idea (for simulation in NS-2) (better try reactive + geographic/load aware routing it will improves your performance when compared with hybrid and proactive, hybrid and proactive consumes more energy compared with reactive + geographic/load aware routing)