I believe it would be wise that the one item of communication would be to dispute the claim.
I disagree - at least until ryguy has the opportunity to speak with his mother's lawyer to check on the advisability of such a communication.
Right now, ryguy says he has put nothing in writing. I believe he would be smart to keep it this way at this point, whether what is in writing is denying claims made by the ex-employer or not. He should not communicate at all with the former employer. I do not see how this can benefit him and it could (some way, somehow, not sure how) be used against him.