I just purchased Avast Internet Security and VPN. I also have Malwarebytes and C-Cleaner installed and want to know if either of these programs are still necessary or should I uninstall?
Regarding Avast & Malwarebytes, see: https://forums.malwarebytes.com/topic/200324-exclusions-for-avast-users/
I personally haven’t had Malwarebytes find anything relevant in several years.
Avast doesn’t only check for virus, rootkits and, trojans. It also blocks general malware.
Ccleaner is used to delete clutter from your system that’s why it’s original name was Crap Cleaner. (Yes, some of us go back that far. ) 
Malwarebytes has always been good for removing stuff from your PC if anything gets through AVAST but I have to say that apart from files retrospectively re-classed as PUPs (potentially unwanted progams) that has not happened for a long time. However it is still potentially useful to have a backup AV/AM tool, one which does not interfere with your main AV, to scan and recheck a file or whole system for peace of mind.
If it is set to run at startup I’d stop that, waste of resources, but I certainly wouldn’t delete it. Use it as an on demand scanner.
CCleaner, despite AVAST’s fumbling and messing around, almost ruining its well deserved good reputation, is still an important and highly useful, comprehensive maintenance and management tool. Other tool-sets can do what it does but few do it as well and as reliably. It also has, like other Piriform originated software, IMHO, a one of the best designed, noob friendly, unintimidating GUIs you’ll find.
Agreed.
Always good to have a second opinion on system security. If you have the resources running real time imo never hurts.
Edit: In years of use with Avast I’ve personally not experienced any conflict
The last time I scanned with Malwarebytes it found 17 PUPS . A quick scan using Avast didn’t find any so I’ll keep using Malwarebytes.
What you forgot to mention was information about those PUP’s. Were they truly unwanted or just items Malwarebytes considered unwanted?
I would not be surprised if those PUPs were mostly Auslogics files.
A few years ago they blotted their copy book when one of their products started installing some of their other products whether you wanted them or not. The opt out did not work apparently and so they received some very bad press.
The result was that all Auslogic software was tainted with suspicion and, as I mentioned earlier, almost overnight retrospectively redefined as PUPs.
I remember doing a full system scan with Malwarebytes and everything was perfect but a couple of weeks later I did the same thing again having installed nothing new and it reported almost a full page of PUPs, all Auslogics files, reg entries etc.
I was not using any of their software at the time but had used their ‘Pro’ Defragger on my old laptop. After that died I’d backed up its HDD to a new PC and an external HDD and it was all that stuff which was now reporting as PUPs.
Even a year on from that I’d forgotten I’d archived some Auslogics’ installers on flash drives and when I did a full system scan with one of those attached suddenly Malwarebytes was reporting them as another slew of new PUPS.
Yes, but I wouldn’t run two AV products at the same time. I use Malwarebytes only on-demand.
That’s fine, for me and so many others, Mbam and Avast have been compatible from the beginning.
No worries, just stating my experience on both forums.
Malwarebytes is not a AV
It does not target real virus or script, doc and media files
That’s correct. 
They were truly unwanted
Truly unwanted would have been removed by Avast. Can you be more specific?
What were the removed items ???
Side note, you’ve to enable PUP detection in Avast (it’s off by default).
Good point, Asyn.
I have it enabled