WP errors

My website is experiencing errors due to plug-ins I have access to the back end of WordPress and my issue has started just today. I would like to hire someone to resolve this issue quickly, efficiently and professionally. Prior experience of working with WordPress is essential and the ability to provide a fast resolution for any issues. Please only apply for this project if you are confident that you can resolve the errors.
Notice: Undefined index: query in html/wp-content/mu-plugins/class-po-mu.php on line 120
Eating up lots of memory for unknlwn reasons:

Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 20480 bytes) in /home/exciti8/search.excitingads.com/html/wp-includes/plugin.php on line 164