Hey @KaptainKopter and welcome to the forums!
Zoho is an excellent solution for a small (and even larger) business. I’m personally using it for mine. Especially the Workplace Pro. Besides the cloud storage and - of course - the email and the other amenities, it also offers Cliq, which is a Slack equivalent that allows you to create chat channels and invite guests - with whom you can text and video-chat to help them out with issues. It offers clients for all main operating systems and also runs on mobiles as well.
Another advantage the Workplace has is its own Social Network (like Facebook), which is private and controlled by you.
Its Meetings application is sufficient for video chat and share screen, not taking control of another system for assistance purposes. For that purpose, there are different tools, but they also require installation on the client-side. If you don’t want to go into the lengths of installing VNC-enabled applications, such as Remmina (which may have a bit of a tedious setup), I would highly recommend TeamViewer. I’ve helped quite a few people that way and it’s cross-platform (with a Linux application as well). I haven’t tried Assist yet, so I can’t offer any input.
If you are looking for an extremely secure (and fast) video chat system, I personally recommend Cisco’s Webex. It has more collaboration tools and the clients can just join from a browser, without having to download and install an application (like Zoom demands).
Proton is a great alternative, but it’s still under development on its suite. It’s new, Unlimited version offers email, VPN and cloud storage.
For Antivirus stuff on Windows, this is a long subject. In my book, if people act carelessly enough to have to rely on an antivirus, then sooner or later, their system will get infected no matter what. There is nothing to protect them against 0-day malware, other than good education on how to act online. Believe it or not, even Windows Defender can do a good job regarding viruses. I have familiarized myself with these techniques and it has kept my systems clean for a really long time.
However, if you absolutely have to suggest something, the two top-of-the-line motherships of the Antivirus applications are Kaspersky (I know, Russian, so people may be reluctant) or BitDefender. Those two have state-of-the-art engines with the necessary heuristics to stop nearly everything.
I hope the above helps!