Although, on the other hand, that cash sitting there is going to be eaten up by your son's education, while if it was equity in a home or a small business, it would not be considered available to him for funding his education. (I think that may also be true for funds that are in some sort of tax preferred retirement form -- like an IRA or 401(k).) And, unless he goes to an extremely cheap community college or state school, AND lives at home, I don't know if that $49k is going to go far enough to pay for his education. If you don't have the money available, he's much more likely to qualify for financial aid that can make a big difference to him long term.
Ditto what the others have said about the other expenses of owning a home.
Why a house on land? A house on a tiny lot is far more economical, easier to care for, and less expensive to maintain. I live in a small house on a small lot in a city and still have PLENTY of space for growing food, planting fruit trees, putting in flowers, and doing all those other warm and fuzzy land things. Unless you've lived with a sizable bit of land as your sole responsibility so you already know what you're getting into, maybe you want to reconsider that part of the equation. A smaller place will also have you paying far less in taxes and insurance, easing your day to day cash flow concerns, and leaving you a little more wiggle room to handle the ups and downs of normal financial life, which as a single Mom you have to absorb on your own. Good luck, whichever way you decide to go.