Create a child theme
and paste the following code in footer.php of child theme
<?php if( is_active_sidebar('footer-a') || is_active_sidebar('footer-b') || is_active_sidebar('footer-c') ) : ?>
<div class="footer section large-padding bg-dark">
<div class="footer-inner section-inner">
<?php if ( is_active_sidebar( 'footer-a' ) ) : ?>
<div class="column column-1 left">
<div class="widgets">
<?php dynamic_sidebar( 'footer-a' ); ?>
</div>
</div>
<?php endif; ?> <!-- /footer-a -->
<?php if ( is_active_sidebar( 'footer-b' ) ) : ?>
<div class="column column-2 left">
<div class="widgets">
<?php dynamic_sidebar( 'footer-b' ); ?>
</div> <!-- /widgets -->
</div>
<?php endif; ?> <!-- /footer-b -->
<?php if ( is_active_sidebar( 'footer-c' ) ) : ?>
<div class="column column-3 left">
<div class="widgets">
<?php dynamic_sidebar( 'footer-c' ); ?>
</div> <!-- /widgets -->
</div>
<?php endif; ?> <!-- /footer-c -->
<div class="clear"></div>
</div> <!-- /footer-inner -->
</div> <!-- /footer -->
<?php endif; ?>
<div class="credits section bg-dark no-padding">
<div class="credits-inner section-inner">
<p class="credits-left">
? <?php echo date("Y") ?> <a href="<?php echo home_url(); ?>" title="<?php bloginfo('name'); ?>"><?php bloginfo('name'); ?></a>
</p>
<p class="credits-right">
<span><?php printf( __( 'Theme by <a href="%s">Anders Noren</a>', 'hemingway'), 'https://www.andersnoren.se' ); ?></span> — <a title="<?php _e('To the top', 'hemingway'); ?>" class="tothetop"><?php _e('Up', 'hemingway' ); ?> ↑</a>
</p>
<div class="clear"></div>
</div> <!-- /credits-inner -->
</div> <!-- /credits -->
</div> <!-- /big-wrapper -->
<?php wp_footer(); ?>
</body>
</html>
What it does is checks whether any of the footer widget areas are active by using is_active_sidebar() function and then display footer area accordingly ..