This relates to a cookie that is usually the consequence of an adware or advertising software infection. Maybe it is something which was left over after Malwarebytes cleared all the other bad stuff yesterday.
You could see whether clearing the cookies (maybe by using a program such as CCleaner) will get rid of it (N.B. never use the registry cleaner section of CCleaner).
If that fails to work, then I think perhaps that a visit to the Virus and Malware Section of GTG could well be a good idea.
EDIT FYI the Ghostery normally encountered is a free privacy and security-related browser extension. It does not however appear that ghostery.js has any connection to the usual Ghostery which can be found at ghostery.com.
Edited by Channeal, 07 July 2017 - 10:20 AM.