The emergence of context-aware systems has highlighted the requirement to reduce complexity in developing the systems by establishing a context middleware. The middleware aims to provide support for managing context independently from applications and enhance generality and reusability of context sources for multiple applications. In this paper we propose a novel framework for managing context in Mobile Ad Hoc Network Environment (MANET). We model contexts and situations based on the concept of situation space in Context Spaces theory and integrate the model with Dempster-Shafer rule of combination for situation reasoning. Furthermore, we incorporate reliability of information in the fusion mechanism based on discount rule to adopt uncertainty factor that may exist due to limited and uncertain evidence in the host’s environment. Finally, the implementation and experimentation issues of the prototype are also discussed.