The best way to protect yourself is knowledge. If you get an unsolicited phone call from someone claiming to give you government money, ask them to put the offer in writing so you can have your attorney review it. Generally the federal government does not distribute funds directly to an individual. The individual usually must apply through a licensed lender who will pass the application on to the authorities and organizations and will contact you with information on the funding.
Another sign of a scam is if someone offers you information on government housing grants or promises you funding if you pay a fee. This especially happens in areas that are hit by natural disasters. While a government housing program may have very stringent criteria to qualify, fees are never part of the qualification.
Websites to assist in finding government housing programs