This fight pits you against three Wolfs, everyone has 10,000gp each and you have an almighty hill! Alas, you face one of the hardest foes in the game who will seek to shell you constantly and murder you if you take but a moment of rest.
The trick to defending yourself is to be fast, fight back against siege weapons, and keep your defenses manned at all times. You want to build three adjacent square towers facing all three Wolfs, manned by two mangonels, one ballista, 10 archers, and 5 crossbowmen each (for starters) For the northwest blue Wolf, have the mangonels shell his closest gatehouse. For the others, shell his towers manned with siege equipment. Place braziers on all your towers for extra damage. I have seen other walkthroughs that advise enclosing your keep; I personally NEVER enclose my keep and instead rely on a large number of archers and crossbowmen to kill anything that comes near. You should probably use your starting pitch to create a ring of pitch ditches around your northwest, northeast, and southeast sides (neither of them actually managed to get that far with swordsmen or pikes however).
It will be touch and go for a long while; I placed only as much stockpile as I needed to preserve farm land. I used wheat and hops to afford heavy taxes, built several fletchers to keep my towers manned, built stone and iron all around the starting island, and eventually built up a force of roughly 40 ranged units to guard workers as I expanded to the lower ring of resources to the west and southwest.
NOTE: The NE and SE Wolves will constantly be shelling your towers and killing your guys. Keep your towers repaired and manned with ranged units and siege or you will leave yourself open.
This may be due to peculiarity of luck, but for some reason before long all three sort of shut down, having seemingly run out of gold and were unable to do much (I did send a few slave raids now and then to take out what I could, but this was an errant hobby and not a dedicated strategy). Blue Wolf in particular seemed to have spent all his money on fat walls and his people seemed trapped in their gatehouse. Until I got enough security and resources production I could poop out macemen at a constant rate, I placed a church and cathedral for popularity and built a fat wad of monks. Blue Wolf has moats protecting his things but when I attacked him he only had a few ranged units peppering me. I sent 150 monks to tear down his walls, 15 macemen to fill his moats and sent to monks to kill him.
As long as you keep your defenses manned the other two should not be much of an issue. They will have more siege equipment and men probably but enough trebuchets and macemen should get the job done.