PUP.Optional.Wajam is the detection name for Wajam, a browser add-on marketed as a “social search.”
You can find a description of one variant in the blogpost TopFlix a DNS Unlocker variant.
The PUPs in this family are usually included in bundlers.
A Removal Guide for TopFlix and other members of this family can be found on our forums. There you will see that Malwarebytes completely removes this threat. No further cleanup is required. In some cases you may be prompted for a second reboot. This is necessary to restore your internet connection.