The Special sort of generic IoT network namely Hierarchical IoT Network (HIoTN) is one in which a client can legitimately get to the continuous information from the sensing nodes in a protected generic IoT networking environment especially for particular application. This innovation serves a platform for a new protected lightweight unimodel biometric-factor remote client verification system for HIoTNs in prior, called the Client Validated Biometric Key Administration Convention (UABKMP). These unimodal biometric systems possess various limitations such as Noisy data, Non-universality, Spoof attacks etc., which may greatly affect the overall security of the user. In this work, a new multimodal biometrics based temporal credential-based lightweight user authentication system is intended to manage this significant issue in the HIoTN setting, would be called the Secure Multimodal Biometrics-based User Authenticated Key Exchange Protocol (SMBUAKEP). In addition, fuzzy commitment methodology is greatly utilized in this research for the purpose of multimodal biometric verification. In this research, three approaches namely Real-Or-Random (ROR) is utilized for detailed security analysis using formal security, Automated Validation of Internet Security Protocols and Applications (AVISPA) tool for formal security verification and SMBUAKEP for informal security analysis which has the ability to avoid multiple known attacks. An exhaustive similar examination for SMBUAKEP and some other pertinent frameworks has been accomplished, and the exploration shows that SMBUAKEP offers better security and functionality features and diminished expenses in both processing and correspondence communication comparative with existing frameworks, for example, UABKMP and UAKMP.