With more and more elders in most countries, the health and safety issues become the primary concern for elderly people because ageing is often associated with physical and cognitive impairments. In order to provide intelligent assistive services for elders, in this paper, we propose an integrated service platform that can accommodate safety assurance, daily activity assistance, and health support services. Specifically, the platform takes care of anomalous events detection, daily activities tracking, and health status monitoring leveraging stationary sensors deployed in living environments and mobile sensing artifacts carried by elders. The services in this integrated platform can ensure safety and independency of elders, they can also help them sustain and/or improve health condition with personalized health support. Based on the proposed platform, we present a case study of assistive safety assurance service wandering detection, which monitors an elder's outdoor movements by using GPS sensor embedded in smart phone and recognizes the lapping or pacing movement pattern to find potential wandering behavior. The experimental results show that our method works well in detecting wandering behavior in terms of detection rate and false alarm rate.