Without knowing the table structure you can try something like:
SELECT *
FROM blogs
JOIN b_comments ON blogs.blog_id = b_comments.blog_id
You may want to use a LEFT JOIN
if you want to return blogs that do not have comments.
Update
//get blog posts
$blogID = intval($_GET['id']);
$blogTitle = null;
$pubDate = null
$blogCat = null;
$blogAuthor = null;
$blogImage = null;
$blogContent = null;
//get comments
$getComments = $link->query("SELECT a.blog_title, a.pub_date, a.category, a.author, a.image, a.content AS blog_content, b.id, b.user_name, b.date, b.content FROM blogs a JOIN b_comments b ON a.blog_id = b.blog_id WHERE a.blog_id = " . $blogID . " ORDER BY b.date DESC");
if(!($getComments->num_rows > 0)) {
echo "<div id='commentArea' style='display: none;'>";
echo "</div>";
} else {
while($comRow = mysqli_fetch_assoc($getComments)) {
if(empty($blogTitle)) $blogTitle = $link->real_escape_string($row['blog_title']);
if(empty($pubDate)) $pubDate = $link->real_escape_string($row['pub_date']);
if(empty($blogCat)) $blogCat = $link->real_escape_string($row['category']);
if(empty($blogAuthor)) $blogAuthor = $link->real_escape_string($row['author']);
if(empty($blogImage)) $blogImage = $link->real_escape_string($row['image']);
if(empty($blogContent)) $blogContent = $link->real_escape_string($row['blog_content']);
$commentID = $link->real_escape_string($comRow['id']);
$comAuthor = $link->real_escape_string($comRow['user_name']);
$comDate = $link->real_escape_string($comRow['date']);
$comContent = $link->real_escape_string($comRow['content']);
$comDate = date("F jS, Y H:ia", strtotime($comDate));
}
}