How do I know a patch is safe?
You can't.
However I played long time with 1.0c (and 1.0e) patch, because on 1.0 there were some known hacks. You can just download AOE 2 from any torrent site or from voobly (but their links seems to not working). But you risk same as downloading it from www.aoccs.net
If you want to be sure, just play on steam, there is no big difference.