Well I was going to suggest a program called Ameridream but when I went to see if it was still even a possibility I found some bad news. Link:
AmeriDream, Inc. - Down Payment Assistance For Home Buyers - Home
Seems that congress has put an end to it as of 10/01/2008
This was an excellent program, one that I used when I bought my first home. The way it worked was the owner of the home would deduct "X" amount of dollars off the home to be put towards the downpayment. The buyer used this as the downpayment and the seller got a big tax credit for it. Would have been perfect for your situation. If the house was worth 135K and your mother owed 100k, she could have priced it at 110k, donated 10K to ameridream which would have been used for your downpayment resulting in you borrowing 100k from the bank. Would have solved the problem, got you in a home, and gave your mother a big tax break on the sale.
Leave it to Congress to screw up a good program! And one that didn't cost the
Government anything to keep going.