Some time back Dreamhost stopped supporting PHP56 and moved to PHP7.x by default and some of my sites stopped working.
However there is a way to run those old site. Just add the following lines in your .htaccess file.
AddHandler fcgid-script .php
FCGIWrapper "/dh/cgi-system/php56.cgi" .php
Enjoy! but upgrade them to Drupal 8, if your client is paying for it ofcourse.