Arduino open door (outdoor) tonemelody
I'm not quite sure I understand the logic of what you're asking. Your description is a little vague. Maybe if you provided more information about what the signals are, what they mean, and where they come from, it may help.

However - if you want the melody to play when both inputs are LOW you should change:

if(StatOutDoor == LOW &amp;&amp; StatInDoor = LOW){
      PlayMelody();    
} 


to:

if(StatOutDoor == LOW &amp;&amp; StatInDoor == LOW){
      PlayMelody();    
} 


Note the use of == not = to denote equality (= is assignment).

Also the use of a 3.3 second delay in your else will show everything down to a crawl when StatInDoor is HIGH.