With the huge advancements of mobile computing due to the enormous increase in portable wireless devices, Mobile Ad hoc Networks (MANETs) became an important aspect in the world of wireless network communications. With some unique features such as scalability, fault tolerant and autonomous systems enable a network to be setup with or without any trusted authority. This makes MANET suitable for the emergency and rescue operations. During an emergency situation, there is a need for the data to be shared with the rescuers. Prior accessing the information in emergency services, nodes in MANET need to be authenticated. However due to wireless nature that MANET inherit, nodes are susceptible to attacks hence a secure authentication mechanism is required as authentication is the first defend mechanism. This paper review the authentication models in MANET and proposed the suitable model to work under our proposed access control model called Heterogeneous Access Control Model (HACM). HACM is an expanded proposed model from our Group Based Access Control Model (GBAC) where access to information is classified into general and sensitive based on the Group Role (GR) and User Role (UR) of rescue members during emergency services. The HACM model introduces Heterogeneous Access Level (HLA) where access to information is based on level of information sensitivity, which is mapped with user-role in the group, created at the emergency area. The level of information sensitivity depends on how disastrous or the severity of the emergency situation.