500 Error on every page

My blog is at https://morbidentree.tk/blog
My WordPress version is 4.0.1

Whenever I go to my site I get a 500 error, it happens on every page. I know that a 500 error is a server related error, but my host said that the server shouldn’t be throwing errors.
Only thing that I can think of that would cause this is the .htaccess file. The following is my current .htaccess file:

# BEGIN WordPress

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . blog/index.php [L]
</IfModule>

# END WordPress

I didn’t do anything that would cause this to happen. My site was just sitting there unattended for a few days and it was like this when I came back to it.

Any ideas?