There are plenty of sources for financial aid. I'd do them in this order.
1) Have her work as a TA or an RA. Typically you get free tuition, free or drastically reduced health insurance, and a small monthly stipend.
2) Have her go to the financial aid office and ask if there are any school grants to apply for. These typically have many conditions - like must be a 120 year old woman from a hometown of under 10 people in the state of Alaska and who wears glasses to correct for astigmatism and who will do work as an English major to have a job at a chemical plant. But they do exist and they are free money. Ok I exaggerated, but my point is the same, they are hard to get.
3) Have her fill out the FAFSA. Yes, FAFSA is for graduate students too. No she won't get a Pell grant (undergraduates only). But she can get loans to cover the costs. The interest rates right now are under 3%. Most loans are interest free and payment free until 6 months after graduation (unless you and your wife have a high income). Boy there is a lot of misinformation here in this thread.
4) She can try for a bank loan. Interest rates will likely be high and payments will likely start right away.