Final answer:
The most appropriate action for a nurse when treating cocaine addiction is to provide individual and group psychosocial therapy with a focus on drug counseling.
Step-by-step explanation:
The most appropriate action for a nurse to take when a patient is admitted to the healthcare facility for the treatment of cocaine addiction is to provide individual and group psychosocial therapy with a focus on drug counseling. This approach addresses the psychological dependence and withdrawal symptoms associated with addiction. Administering THC or naloxone would not be suitable in this case, as they are specific to different substances. Initiating maintenance therapy with methadone would be appropriate for heroin addiction, but not for cocaine addiction.