Buses is the usual plural of bus in both British and American English, ignoring the typical doubling of consonants after a short vowel. The form busses is less common.
"buses." YourDictionary, n.d. Web. 25 May 2018. <http://www.yourdictionary.com/buses>.
buses. (n.d.). Retrieved May 25th, 2018, from http://www.yourdictionary.com/buses
See PC data buses.