Then i think they have given it wrong. Take 4 vertex and make a square. No of matching is 2 while now take a disconnected graph in which no edge is there . Matching = 0. so md < mc graph. now for equal case take the same vertex set make 2 components such that each component contain 2 vertex and one edge. so now maximal matching in such a graph is 2. which is equal to the mc.