Network operators are more than ever overwhelmed by increased capital investments and operational costs incurred due to the explosive mobile data traffic growth. An efficient strategy in managing operational expenditure within limits without sacrificing end-user satisfaction is to offload the traffic of content dissemination from the network backbone to local road-side units (RSUs). Allocating suitable subsets of contents to each RSU cache so as to maximize the hit ratio of requests made by vehicular entities is an optimization problem of paramount value. In this paper, we address the issue of content dissemination in a socially-aware hybrid environment with mobile end-users, wherein an overlay network comprising of a social network over a cellular vehicular network is considered. In this setting, vehicles represent the mobile nodes that obtain requested contents either from base station or from local RSUs, if available. By employing a mobile RSU that accounts for the social characteristics of the underlying network, we introduce a novel approach for content distribution in an urban environment. Results from simulation experiments reveal an average improvement of 6% in network throughput for the proposed method as compared to conventional content dissemination counterparts.