The correct answer to this open question is the following.
The connection between the Montgomery Bus Boycott and the founding of the SCLC is that the Southern Christian Leadership Conference was founded by of the most important leaders of the Montgomery Bus Boycott, Dr. Martin Luther King Jr.
Let's have in mind that the Montgomery Bus Boycott started on December 5, 1955, when African American woman Risa Parks was arrested by the Montgomery Police because she was seated in the white section of the bus and refused to give her seat to a white man.
Dr. King, the most important leader of the Civil Rights movement in the South of the United States, was a prime figure of the boycott that ended until December 21, 1956.
On January 10, 1957. Dr. Martin Luther King Jr. became the first President of the Southern Christian Leadership Conference (SCLC), whose headquarters were in Atlanta, Georgia.