In the interest of achieving higher reliability, mobile ad hoc grid should apply a fault tolerance in resource allocation scheme. Resource allocation plays a critical role in mobile ad hoc grids due to the dynamic nature of nodes connection. Allocating appropriate resources for the tasks can avoid uncompleted tasks and ensure service reliability. The authors propose two approaches for avoiding tasks failure due to nodes mobility. They are selecting resource nodes, which have corresponding mobility with resource management system, and implementing task replication strategy.