How to display custom option field in woocommerce orders in admin panel?

You have forgot to save custom meta field data so check it below code I have done it. Reference

add_filter( 'woocommerce_checkout_fields' , 'occasion_checkout_field_update_order_meta' );
function occasion_checkout_field_update_order_meta( $fields ) { 
$fields['billing']['occasion'] = array( 'type' => 'select', 
    'id' => 'occasion', 
    'placeholder' => __('Select Occasion', 'woocommerce'), 
    'required' => false, 
    'class' => array('form-row-wide'), 
    'clear' => false, 
    'options' => array( 
        'Birthday' => __('Birthday', 'woocommerce'), 
        'Anniversary' => __('Anniversary', 'woocommerce'), 
        'Congratulations' => __('Congratulations', 'woocommerce'), 
        'Sorry' => __('Sorry', 'woocommerce'), 
        'Good Luck' => __('Good Luck', 'woocommerce'), 
        'Thank You' => __('Thank You', 'woocommerce'), 
        'Get Well Soon' => __('Get Well Soon', 'woocommerce'), 
        'Love' => __('Love', 'woocommerce')
    )
); 
return $fields; 
}
add_action( 'woocommerce_checkout_update_order_meta', 'occasion_checkout_update_order_meta' );
function occasion_checkout_update_order_meta( $order_id ){
    if( !empty( $_POST['occasion'] ) )
        update_post_meta( $order_id, '_occasion', sanitize_text_field( $_POST['occasion'] ) );
}
add_action( 'woocommerce_admin_order_data_after_billing_address', 'occasion_edit_woocommerce_checkout_page', 10, 1 );
function occasion_edit_woocommerce_checkout_page($order){ 
    echo __('Occasion').': '.get_post_meta($order->id, '_occasion', true ); 
}