Many image memes are just plain silly but this one has considerable truth in it. It is true that Martin Luther King owned guns and, at times, was protected by armed volunteers. It is a matter of record that he applied for a concealed carry permit in Alabama. Unfortunately for King, Alabama was a de facto shall-issue state at the time and the local police decided he was not a suitable person.
It is also a matter of record that then Attorney General Robert F. Kennedy approved the FBI’s wiretap and clandestine microphone campaign against King. This surveillance lasted until his assassination in April 1968.