How do I deal with a moderator or somebody who went and down voted 10 or more of my old answers. I think just to spite. All were done within a few minutes of each other though those answers were written over a long period of time. Is there a way to monitor the moderators, curtail the abusers?
The system will detect them if made in a short period of time, or against the same user, or both. Give it a day or two and you'll almost certainly find them reversed.
And you only need 125 rep to down-vote. No reason to suspect it's a moderator or other high-rep user.
Disclaimer: it wasn't me.
However, I notice that you have a lot of downvotes, and in many cases, more than one, so it's not just one person's vendetta. I notice, also, that a lot of these downvotes are on answers to questions that are closed as off-topic,. In this case, those downvotes are probably not out of spite, but just to encourage you to delete them -- because answering off-topic questions invites more people thinking "sure, it's off-topic, but maybe someone will answer anyway", which decreases the sites' focus and therefore quality.
So, I do encourage you to consider deleting some of those answers and to not encourage off-topic questions. Most of these are equipment recommendations, which we have a long history of struggling with --- see Time to propose a Camera Shopping Stack Exchange? and related links for osme of the background.
Now that I look, I notice a few others of your answers that, honestly, I might have downvoted had I noticed. For example, Why is nothing appearing on my NEX 5n LCD screen? doesn't really answer the question at all, just gives some general advice of mixed quality (vague badmouthing "some manufacturers, not good; suggesting to send in for repair, possibly good, although who knows if that was really needed in this case; saying "who knows" as to whether it might be fixed for free, not so helpful, as it is certain to be fixed for free under warranty and almost guaranteed to not be if not).
Other answers, like https://photo.stackexchange.com/a/64831/1943 don't seem to actually answer the question at all -- it just tells you to call someone else to get your answer. That seems even worse than telling someone "just Google it!". The answers should be ... answers.