Having two sets of parallel lines means that it can either be a rectangle, a square, a parallelogram, or a rhombus.
Having the diagonals congruent makes this figure either a rectangle or a square.
Since the length of the side is not given, we can only assume that this is a rectangle.
Summarizing it all, quadrilateral DEFG is a parallogram that is a rectangle because of the two pairs of parallel lines, and it has congruent diagonals.
