How to solve a problem with family when it comes to rent?

Ok so my father asked me Oct 27th if I could move in dec 1 to his duplex. I'm supposed to be paying $690/mth for a 2 bedroom. On Nov 3rd I was notified by my current landlords I have to stay until Jan 1st to give adequate notice. My dad said he needed to clean because the other tenants that were in there had a cat so I wouldn't move in right on the first anyhow. I spoke to my father and he said he wanted me to atleast cover the hydro for the month im not there. I agreed, but now he's asking me to pay for the month of dec and the hydro. That means I have to pay for two apartments for the same month! I'm on a tight budget right now and I can't afford it at all. I hate to say I can't move in..but I'm really tight and I dont want a fight to arrupt. Should I look for someone to move in dec 1 or try to bargain with him!!:(