value of metadata is null wrong use of if statement

Try:

$rating = get_post_meta($post->ID, 'ratings_score', false); 
var_dump($rating);

You will notice that you get an array, even if your ratings_score is 2. To wit:

array(1) {
  [0]=>
  string(1) "2"
}

That will never equal 2 so your condition will never work.

The third parameter of get_post_meta() if set to true will collapse that array to a scalar, and that will work.

$rating = get_post_meta($post->ID, 'ratings_score', true); 
var_dump($rating);

Note that if your post has multiple ratings_scores you will only get one of them and it may not be the one you want.

To make this work with multiple ratings_score entries use:

$rating = get_post_meta($post->ID, 'ratings_score', false); 

if (in_array(2,$rating)) {
  echo 'found it';
}