coloque \.php$
entre aspas duplas
<FilesMatch "\.php$">
SetHandler application/x-httpd-php
</FilesMatch>
reiniciar apache2
:
sudo service apache2 restart
se isso não resolver o problema, altere FilesMatch
para LocationMatch
e reinicie apache2
<LocationMatch "\.php$">
SetHandler application/x-httpd-php
</LocationMatch>