Thank you for that further information. I can amend my advice as follows.
Aside from ensuring that you return her documents to her, there is nothing else that you can do in respect of the other party’s behaviour. If you make every effort to return the documents to her, she has no basis to make a court application against you and if she did, it would fail.
If she continues to harass you, you may report her to the police who may caution her.
Otherwise, I do not think that this is a matter where any law applies nor one that the courts can resolve.
In order for the civil law to step in and assist a claimant, they must have suffered some form of tangible loss, such as loss of business profits as a result of a breach of contract or infringement of intellectual property rights, damage to personal or business reputation (i.e. Defamation, Libel, Slander), wasted monies on purchasing a product or a service that was defective or never provided, personal injury or property damage.
I cannot see any contractual relationship or duty of care in tort between the parties in this matter, nor what damage, financial or other otherwise, they may have lost. Therefore, it is more of a personal dispute rather than a legal and commercial dispute. Overall, I think that the other party is unhappy with your conduct and just “blowing off steam” at you.
You should send one last reply to her that you are not going to respond further to their allegations and leave it to them to instruct solicitors and send a formal Letter of Claim to you before issuing Court Proceedings for recovery of her alleged losses. If this occurs, you should instruct solicitors to advise you on your legal position and defend any claim from the other party.