if u mean g-class monster items, then you get that in the g-class guild quests, but to get there you can look at the hr rank quests to get to hr 3. hr 3 is the g-class quests (from the blue lady).
white monoblos doesn't show up as any guild quest i think, i guess it's only in the village after you kill the normal one .
lord of hunters hr5, land and sky in village left. trying fatalis
weapons: garugaGS,barbaroiGS,eternal schisms,eternal strife,corona,upper b-axe,frost edge+,expert sword,wolf blade,gradios ultimus,legendary blades
armor: garuga,rathalos soul,rathian heart,esp helm,diablo,monoblos,rathalos,basario