Something

on $*:TEXT:/^([!~@.])?(away|brb) */Si:#: {
  set %brb $+ $nick $2-
  set %brbt $+ $nick $fulldate
  if (!$2) set %brb $+ $nick ~~ None Set ~~
  /msg $chan 10 $+ $nick is now away. $chr(124) Reason:4 %brb [ $+ [ $nick ] ]
}
on *:text:*:#: {
  if ( %brb [ $+ [ $nick ] ] ) {
    /msg $chan 10 $+ $nick Is now back. $chr(124) Reason:4 %brb [ $+ [ $nick ] ] $+ 10 $chr(124) Time gone:4 $duration($calc(($ctime - $ctime(%brbt [ $+ [ $nick ] ]))))  
    unset %brb $+ $nick
    unset %brbt $+ $nick
  }
}