What determines which monsters my friends can hunt?
When I send one of my friends on a hunt via Hunters for Hire, what determines which monsters they can hunt and which rank the hunt will be?
You can talk to the Guildmaster in Solo Port Tanzia. By doing so, he will give you the option of what types of quests you want to send your Hunters for Hire on.
I'm pretty sure you can limit it to level of rank, so long as it's not above your rank. ie. You can't send them on a G rank quest if you haven't reached it yourself.
You can't be completely specific about it (ie. Hunt only Gigginox), but you can limit it to area (Tundra, Volcano, etc.), and whether or not you want to hunt large or small monsters. By using these options in combination, you can drastically reduce the randomness of what hunts are presented for your Hunters.