tenant demand pet deposit to be refund

[Kathy Nguyen]

I have a unit that has three tenants lived in there.  2 tenants vacanted and the third one decided to stayed.  One of the girl, who vacated made a pet deposit of $300.  On the pet deposit agreement stated that pet deposit is non-refundable.  She moved out and now she demand refund on the pet deposit.  I told her pet deposit are not refundable but she said in the pet agreement stated it is.  But one of pet agreement section stated:

NON-REFUNDABLE PET DEPOSIT: Tenant will pay a one-time refundable pet deposit of $300.00 if there is no damage in order to have the pet in the unit. ( This section is confusing.  But I think where "Tenant will pay a one-time refundable pet deposit of $300.00" used to be non-fundable but somehow the "non" word got taken out or there's a typo)

3. NO LIMIT ON LIABILITY: The additional security deposit, non-refundable pet deposit in the amount of $300.00 under this Agreement is not a limit on Tenant’s liability for property damages, cleaning, deodorization, ridding unit of fleas, replacements, and/or personal injuries set forth below.

Both contract and the tenant are inherited from previous owner.  The seller didn't pass on the non-refundable pet deposit.  Also I can't do a throughly inspection bc one of the tenant is still there.   How should I approach this dilemma?