(a) Subject to subdivisions (b) and (c), the commission may retain, relinquish to a local agency pursuant to Section 73, or summarily vacate a state highway that has been superseded by relocation.
(b) The commission shall not vacate a state highway unless the commission has first given a notice of relinquishment pursuant to Section 73 and the legislative body of the local agency has protested within the prescribed 90-day period that the highway is not needed for public use and should be vacated by the commission.
(c) If vacation of a state highway would cut off all access to the property of any person which, prior to relocation, adjoined the highway, the commission shall either retain the highway or relinquish it pursuant to Section 73.