The electronic and optical properties of graphane, silicane and MoS2 bilayers, as well as the graphane/MoS2 and silicane/MoS2 hetero-bilayers, are calculated by the first-principles method. The interlayer interactions of all the bilayer systems are shown to be mainly van der Waals. Both the graphane/MoS2 and silicane/MoS2 heterobilayers belong to the type-II heterostructure, which can be utilized in photo-voltaic devices due to the efficient spatial separation of electrons and holes. For optical properties, the distinctions for the imaginary parts of the dielectric function epsilon(2)(omega) between the monolayer and bilayer systems for both the graphane and silicane are more evident in electric vector E parallel to z. However, the differences between epsilon(2)(omega) of the monolayer and bilayer MoS2 materials are more significant in E parallel to x. Broader light absorption ranges of the hetero-bilayers are reached, which can also improve the charge separation of the electron-hole pairs.