It might be worth talking to your landlord to see if there's any chance you could spread out the repayments for the remaining rent over a few more months. Or if you put a deposit down on the house before moving in, ask if they could use that as the last part of your rent instead of you paying it (assuming you've done nothing to the house).
I don't know if you already have an overdraft on a student account, but this could be a good way to get the money you need, as a lot of people have overdrafts while they're studying. Some Universities also do emergency loans or grants if he explains the situation to them.
Also try to cut back on how much you're spending at the moment. Things like nights out could be cut back on, and food bought more cheaply, every little helps.
With regards to the job, how picky is he being? I don't know where you live, but there are always advertisements for cleaners in my local area, usually paying around £7 per hour, he could do that over the summer to save the cash he needs. Or sell some of his belongings like old books/DVDs/do a car boot sale. There are plenty of ways he could raise the cash, it's all about being a bit inventive.
If he has a bit of spare time on his hands, and a bit of money to start off with, matched betting is a good way to get some free cash. It's risk free and using FixTheOdds.com shows you how to do everything so you shouldn't make a mistake. Read up about it and see if it's something you like the sound of. I managed to make £500 in my summer holiday last year so it's worth having a look at. Also whenever I post about matched betting people always attack me and post hate saying "how can gambling be risk free" etc etc well please read up about it before you quote me, thanks!