I found alternative solution for my problem. Instead of using fetch_feed, I used DOMDocument in PHP. This is my code
<?php
$rss = new DOMDocument();
$rss->load('http://techdaily.vn/feed/');
$feed = array();
foreach ($rss->getElementsByTagName('item') as $node) {
$item = array (
'title' => $node->getElementsByTagName('title')->item(0)->nodeValue,
'link' => $node->getElementsByTagName('link')->item(0)->nodeValue,
'image' => $node->getElementsByTagName('image')->item(0)->nodeValue,
);
array_push($feed, $item);
}
$limit = 1;
for($x=0;$x<$limit;$x++) {
$title = str_replace(' & ', ' & ', $feed[$x]['title']);
$link = $feed[$x]['link'];
$image = $feed[$x]['image'];
?>
<a href="http://techdaily.vn" target="_blank"><img class="logo" src="http://techdaily.s3.amazonaws.com/wp-content/uploads/2014/01/techdaily-logo1.png"></a>
<ul>
<li class="thumb">
<a href="<?php echo $link; ?>" class="title" target="_blank">
<img src="<?php echo $image; ?>" alt="<?php echo $title; ?>">
</a>
</li>
<li><a href="<?php echo $link; ?>" class="title" target="_blank"><?php echo $title; ?></a></li>
</ul>