Given points are A(2, 0), B(9, 1), C(11, 6) and D(4, 4).
Coordinates of mid-point of AC are (11+2/ 2, 6+0/ 2) = (13/2, 3)
Coordinates of mid-point of BD are (9+4/ 2, 1+4/ 2) = (13/2, 5/2)
As the coordinates of the mid-point of AC ≠ coordinates of mid-point of BD, ABCD is not even a parallelogram.
Therefore, ABCD cannot be a rhombus too.