For Undead Yard, you have to kill all of the enemies. You'll need to be able to deal a good amount of damage, or else it will take too long to kill them all. It's much easier if you have a weapon with mod slots and a high-level power medal. The maps can be found here: 1st Floor: db.gamefaqs.com/console/ps2/file/digimon_world_4_undead_yard_f1.gif
2nd Floor: db.gamefaqs.com/console/ps2/file/digimon_world_4_undead_yard_f2.gif

In the Undead Yard there is 279 evil digimon in normal mode. The first floor has 156 evil digimon and 2 traps one at the shockgrids and on the left at the empty pharoahmon sarcophaguses. 123 evil digimon on the second floor with 2 traps one at the of the fist main lobby gate And a random one for another mainlobby gate. Finnally 1 secret on the 2nd floor.After you beat the first room on the second floor go beat the evil digimon in the room across from you, then go back and defeat 10 more at the first room. Also don't destroy the tower on the second floor and there is a time limit of 30 minutes.
Have fun with the digimon you get as the reward, no matter what you will get one even as dorumon like i did.

As for Item road I just choose random paths. I beat up 50 evil digimon. And I beat up Shogungekomon the boss you don't relly need to get an item and again injoy the digimon you get.