Question

Which 3 dwarves that were in Thorin's "company" died in Moria

Answer 1

Anyway, on LOTR Wikia, it says the same thing - Dwalin, Bifur, Bofur, Bombur, Gloin, Nori and Dori were alive, while Thorin, Fili and Kili died in The Battle of the Five Armies, Balin died of sickness, Ori got killed by goblins and Oin got eaten by The Watcher in the Water.( you know you could have just searched it that always help)

Answer 2

I believe it was oin oriand balin. Hope this helped!