Set Condition echo function get_post_meta

From your code, this is the part where you can get the mark, modified to get only one:

     $member_id = get_current_user_id();
     $course_id = 1; //i am assuming the ID of the course
     $status = get_user_course_status($member_id,$course_id);
     if($status > 3){
        $mark = get_post_meta($course_id,$member_id, true);
        echo $mark;
     }