These are the instruments that you would typically find in a basic rock and roll band setup during the 1950s.
Electric Guitar
The electric guitar first appeared in Jazz bands just before the 1950s. The electric guitar was made popular by small time performers such as Buddy Holly and Chuck Berry because of how they used it's crisp sounds with their showmanship.
Keyboard
Keyboards and electric keyboards like were made popular in the 1960s by bands like the Beatles and the Rolling Stones. Electric keyboards allowed bands to add sound effects or other instruments to their albums. Early on in the 50s pianos were used in Rock and Roll bands.
DRUM SET
Drum kits have been popular in all kinds of bands since the beginning of the 19th century. They were used in big bands, Jazz bands, rock bands and many other band setups.
double bass
The double bass became popular in the late 40s and was part of the traditional Rock and Roll bands of the 1950s. The double bass was used in genres such as Jazz and Blues in addition to Rock and Roll.
Saxophone
Saxophones are commonly seen in classical music, military bands and marching bands and is sometimes seen in 50s Rock and Roll bands.