c. 254
A class 'C' network has 8 bits available for host machines.
Thus the total number of hosts that can be addressed on such a network is 2 to
the 8th power, or 256; minus the network number (x.y.z.0) and the
broadcast address (x.y.z.255), for a total of 254 hosts.
Reference: Comer, Internetworking with TCP/IP, Chapter 4.