Google "can subcontractor sue homeowner in XX state".
XYZ as a subcontractor, they have no contractual relationship with your parents (homeowner). They cannot sue the homeowner unless the homeowner somehow made certain statement/gurrantee to form an "implied contract". I doubt your parent is even aware of XYZ.
This lien can be removed, whatever you think it will become "active" is probably incorrect. Let me know your state and I can provide some links to local laws.