Someone

on *:TEXT:!away *:#: {
  if (%status. [ $+ [ $nick ] ] == back) {
    set %reason $$2-
    msg $chan $nick is now away, reason: %reason
    set %status. [ $+ [ $nick ] ] away
  }
}
on *:TEXT:*:#: {
  if (%status. [ $+ [ $nick ] ] == away) {
    msg $chan $nick is now back from: %reason $+ .
    unset %reason
    set %status. [ $+ [ $nick ] ] back
  }
}