Every child-placing agency upon placing a child in a foster or an adoptive home shall enter a written agreement with the persons taking the child. The agreement must provide:
1. The placing agency has access at all reasonable times to such child and to the home in which the child is living; and 2. For the return of the child to the placing agency whenever in the opinion of the agency, or of the department of health and human services, the best interests of the child require the return.