Final answer:
The PHN acting to coordinate services and manage costs for a client is best described as taking on the role of a case manager, which involves planning, coordinating, and evaluating the client's care in an efficient and cost-effective manner.
Step-by-step explanation:
In this scenario, the Public Health Nurse (PHN) is performing the role of a case manager. A case manager is a healthcare professional who coordinates all aspects of patient care, which includes identifying the services that best meet the needs of the client, and doing so in the most cost-effective way. As a case manager, the nurse would assess the client's needs, plan and coordinate care, work with service providers, and monitor and evaluate the outcomes to ensure that the client receives the best possible care without unnecessary expenses. This role differs from that of an advocate, counselor, or role model, as it specifically involves the management of the various aspects of patient care, focusing on efficiency and cost-effectiveness.