In this paper, we propose an architecture for the 5G core network using Software Defined Networks (SDN) and Network Functions Virtualization (NFV) technologies. Moreover, based on this architecture, we design a framework for determining the Network Functions (NFs) placement and optimizing the NFVI resources and network response time during emergency situations. This framework is based on a two-stage method. In the first stage of the method, the placement of the SDN Controllers and Virtual Network Functions (VNFs) is determined considering not only latency requirements and load levels but also users mobility and network functions type. Meanwhile, in the second stage, the VNF Infrastructure (VNFI) resources are dynamically optimized according to variations on network conditions.