The mobile social cloud is a new paradigm that combines mobile cloud with social cloud. It can provide users with a safe and reliable resource sharing platform. In the conventional resources allocation, the time overhead is large for mobile users to obtain resources from a remote data center, resulting in significantly degrading quality of users' experience. At the same time, there is little consideration of the trust relationship established by users based on social attribute, which leads to credit risk and low reputation of users in transaction mechanism. Therefore, a novel resources allocation mechanism of mobile social cloud is designed in this paper considering the social and economic benefits of users. Firstly, to promote the sharing of resources among social friends, the improved Gale-Shapley algorithm is used to match appropriate sellers for the buyers in their friend circles. Then, to maximize the use of idle mobile cloud resources, a multi-to-multi buyer bidirectional sealed-bid auction algorithm is used to reallocate resources for the unsuccessfully matching users. Finally, the proposed resources allocation mechanism is simulated. The simulation results show that the proposed resources allocation mechanism in this paper has better performances than the Incentive-Compatible Auction Mechanism in terms of price satisfaction, social reputation satisfaction and success rate of resources transaction.