Just change the signature to the same one you have for displayMatrix (which just takes one matrix). Delete half the code. And call it twice, once for each matrix.
You don't have to pass r2 to multiply since it's the same as c1. In fact, you probably should either check that the user entered the same number for both or don't let the user pick that dimension for the second array; it's already been set by the first array.
Thanks for responding @tpb, but I'm having some trouble trying to achieve what you are saying would you mind showing some sample code or something?
Thanks!