Griefing and duping

Today, I got really p****d and f****d up by griefing. I was gone for only 2 days and all stuff havin any vallue was stolen from my house, even the cactuses. What the fuck do people steal cactuses for. My front windows we smashed. Then my secret stash was robbed and 1 chest destroyed. And the chances of finding the place are really low as it's not visiblefrom overground. Also, the other chest was almost full of duped gravel in stacks of 8. I had most of my diamonds and all my gold and iron there. And other useful stuff. It actually fells more like act of agression, as if some1 hated me. I did kill Austin once when he atacked me when woring on the obelisk site. But I get along good with others. But it still feels and even looks like some1 wants to take revenge on me for something. But as I said, can't think of any1 who would do it, so probably it;s just simple griefing.
Long storry short - we should do something about griefing anf duping. I don't know what. And I need a way of hiding valuable stuff.
Note: I might go rage on someone.
Thank you for your atention