How to show user's social profile avatar using WordPress Social Login 2.2.3

WordPress Social Login 2.2.3 plugin works great for me. Now I am trying to show user avatar on his custom post type. I want to show user's social profile avatar in their posts. I tried following code.

<?php
    $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
    $author_id=$post->post_author;
    $args = array( 'post_type' => 'traveller', 'posts_per_page' => 15, 'orderby' => 'rand', 'paged' => $paged );
    query_posts( $args);
    while (have_posts()) : the_post();
?>
<?php the_title();?><br/>
<img title="<?php the_author_meta('display_name', $author_id); ?>" src="" alt="<?php the_author_meta('display_name', $author_id); ?>" width="150" height="150" />

<?php endwhile; ?>

on the above code, how can I get user's social profile avatar in <img src="">?

<img src="<?php wsl_get_user_custom_avatar( $user_id ); ?>" /> 

not working.

<img src="<?php echo wsl_get_user_custom_avatar( $user_id ); ?>" />

Also not working.

Plugin is: http://ift.tt/1kMkGaO