Not really sure how to tell you if you need it or not, but we were pretty early adopters of Imunify360 and do find it to be quite valuable. Maybe read more on the benefits of it here
The team behind this are the same group that does CloudLinux.
It sounds like the hacker may have left a backdoor which is why they are able to reinfect your website again and again.
You may want to take a look at Imunify360 (a paid solution) which should help with this problem.