The Commission may grant a certificate C to any applicant who does not propose in any way to solicit the transportation of persons over improved public highways outside of the corporate limits of any city or town or to operate upon a regular schedule, but who is privately employed for a specific trip and who will not solicit or receive patronage along the route. But such operators may solicit passengers (a) for destination within the corporate limits of any city or town wherein such passengers are solicited, (b) within a radius of two miles of the corporate limits of the city or town in which he is licensed to do business and (c) upon such highways as are not served by a holder of an A or B certificate.