The Facebook Like Box widget can be optionally included in your feed, but if you’d like to only display the Like Box and not any posts then you can follow these steps:
1) Go to WordPress Dashboard > Facebook Feed > All Feeds and click Add New.
2) Select Timeline for the Feed Type and then select an existing source or click Add New to create a source for a new page.
3) Select the Default template.
4) Go to Feed Layout and set the Desktop and Mobile Number of Posts to 0.
5) Click < CUSTOMIZE to go back, then go to Header and Load More Button, and disable both of these.
6) Go to Like Box and enable this.
Now you can save your feed and copy and paste its shortcode to your page to show only the Like Box.