Reference and details below.

The two permission sets that an administrator should ensure are assigned so the users can access Provider Network Management are Health Cloud Standard permission set and Provider Network Management permission set. Health Cloud Standard permission set grants users access to Health Cloud features, such as Care Team, Care Plan, Timeline, etc. Provider Network Management permission set grants users access to Provider Network Management features, such as Provider Search, Provider Relationship Card, etc.

When onboarding a new business unit to Health Cloud while protecting sensitive data for the existing Service Cloud users, adjusting Organization-Wide Defaults (OWD) is critical.
Recommended Settings:
Health Details to Controlled by Parent or Private:
Ensures that only users with appropriate access to parent records (e.g., Person Accounts or Cases) can view sensitive health-related information.
Person Accounts to Private:
Restricts visibility of patient data at the account level, limiting access to users within the appropriate Health Cloud business unit.
Related Clinical Objects to Controlled by Parent or Private:
Applies restricted access to clinical objects like care plans, conditions, and encounters to ensure that PHI is not accessible to Service Cloud users.
Why Other Options Are Less Suitable:
B . Account and Contract to Private: Relevant for managing non-healthcare data but not directly tied to PHI protection.
D . Contact to Controlled by Parent: While this helps manage access to contact data, it does not address broader clinical objects or PHI.
Reference:
Salesforce Health Cloud Security Best Practices