Then the hospital is the one to go by. Maybe the hospital has decided to only keep you for 8 weeks, but it's their call. Most agencies don't even bother to hold hospitals accountable for the contracts they sign. They're agencies that are exceptions, but seeing that this is a problem your agencies hasn't solved yet, I would take my clue from the hospital.
As for being far from home, and the staff being rude, it might be best to stick it out. Since you only have 5 more weeks. But if this has turned into a mistake you wish you hadn't made.
You can always walk, but I would try to work out something with the agency and the hospital. I'm sure you're aware, that you can't go back if you just walk. But if you have had enough, and can't take anymore, then make sure they don't owe you any money on the day you leave, or you will never see it.
And if you have given them access to your bank account, by signing up for direct deposit, then call your bank and find out how to take this back! The agency could reverse your pay, and take money back out of your account, and charge you for travel expenses, and licensure payment(if they paid this for you), and any other monies they think they can get.
Read your contract carefully, and find out what penalities you have agreed to, and then plan your move, if you can't work things out.

Take care!