How to remove Application.MAC.InstallMiez.BPY & Adware.MAC.Generic.9529

You don't need any AV protection as Macs do not get "viruses". They are selling a cure for a disease that doesn't exist. Macs can get other forms of malware/adware as you've found out. Usually from downloading third party software that contains the malware within the installer.

Download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC and is about the most proven anti-malware software for Mac. There is a free version.

"What is the best and most affordable virus protection available for Macs?"

The best way to protect your Mac is to keep it correct with Apple and don't install any third party junk that claim it will protect you from virus, clean your Mac, improve performance in any way. They all are lying for they don't do any of that. Instead all they do is cause problems.

To get rid of the adware, try Malwarebytes for Mac — Mac Antivirus Replacement | Malwarebytes

See this article for manual removal of weknow:

http://www.free-uninstall.org/how-to-uninstall-remove-weknow-ac-from-mac/

Do not download any of the suggested apps.

To understand how to prevent these browser redirects and adware read this User Tip:

Effective defenses against malware and other threats

You can run Etrecheck It is a diagnostic tool that's very useful to us in finding problems. It will provide a snapshot of your system and identify places where the malware may be installed and allow you to remove it. After it runs post the log file here. It will contain no personal information.

Uninstall Avast as per the developer's instructions. No Anti-Virus software or so-called “cleaning” apps are needed or recommended for Mac OS. They can conflict with Mac's own built-in security. At best they will slow your Mac by using unnecessary resources and at worst will bork your entire system.

As far as Google is concerned look in Google preferences > Extensions and if here is an unknown extension delete it.

The articles that were posted cover the bases as far as I know. I not sure why it persists.

You have AVAST installed. You should remove the components as the developer recommends on their website.

Interesting, which cleaner was it? At any rate I'm glad you found it.