Emergency button

That Emergency button only appears after the phone has been woke up and there is a failure of unlocking. Somehow your device is able to react through your clothing to push buttons for it to be a "butt dial". You may wish to consider a different method of carrying your device, or get a case that can cover the screen.

You don't. Cell phones must be able to call emergency services, whether they are locked or not. Even those without active service must be able to do so.