How to conditionally add a widget via a hook in functions.php

One thing, that is off topic, but catches my eye at first glance, is that the php-code and the div-tag in the template are nested in a wrong way. They should be nested like this:

    <div class="twocol-one">
        <?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('fox_home_news_widget') ) ; ?>

            <p>this is a test</p>

        <?php endif;?>
    </div>

And you are missing the closing ?> on the endif-statement.