The decentralized and infrastructure less feature of Mobile Ad-hoc network (MANET) has made it a potential networking solution to be used in major applications ranging natural disaster management, vehicular communication, industrial communication etc. Though, being a dominating mobile communication system, exceedingly high network topology and mobility pattern in MANETs make it trivial to achieve Quality of Service (QoS) delivery, particularly for event-driven (mission-critical) communication. With this motivation, in this research paper a robust QoS Oriented Cross-Synch Routing Protocol for Event Driven, Mission-Critical Communication named Q-CSRPM has been developed for MANET. The proposed Q-CSRPM routing protocol exploits cross-layer routing architecture by applying network layer, MAC layer and physical layer information of IEEE 802.11 standard to perform optimal best forwarding node selection and reliable path formation. Q-CSRPM protocol performed proactive node management, service differentiation based data prioritization and resource scheduling, and dynamic buffer assessment based congestion detection at the network layer, dynamic link quality estimation and packet velocity estimation at the MAC layer, and PHY switching control at the physical layer of the protocol stack. Q-CSRPM applies dynamic link quality, congestion probability and packet velocity of a node for best forwarding node selection to form forwarding path. The node information sharing across the layers of protocol stack enables optimal BFN selection and routing control. It strengthened Q-CSRPM to exhibit 98.2% and 93% of packet delivery ratio for real time data and non-real time data respectively. A minimum of 2% deadline miss ratio was observed.