LinkedList Stack Implementation
This looks to me like it will work as intended. I have a few suggestions for improvement though:


You keep the count variable up to date but never use it's value for anything. You can either remove it or provide a size() method.
You might change your push() method to



public void push(Object item){
   top = new Node(item, top);
   count++;
}



If top is null, you set node.next to null in the Node constructor anyways.
 - If you do this, you can subsequently delete the Node(Item) constructor


I personally would make the item and next member variables in Node final to prevent accidental mutations
(Instead of accepting Object as your items you might want to introduce Generics into your class. But this is an advanced topic and is maybe too hard for you as a beginner)