grounds for defamation

A couple months ago a girl stole from me and I continuously asked her if she knew where my property went. She kept saying no, weeks later a detective contacted me stating that he found my property in a pawn shop and was going to press charges. When I let the girl know, she then came clean asking me to drop the charges but I did not. Me and this girl work together so we speak when we have to and it is always cordial with no problems. I commented on a status of hers on Facebook and her mother replied to me under the same status stating that I was a stalker and I ruined her and her daughters life. Is this grounds for defamation? I did not ruin their lives, she stole from me and I most certainly do not stalk them. This was under a public Facebook status and many people sent me screenshots before I saw it for myself.