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Hello, my name is ***** ***** I will be helping you today. The only way that you could be held responsible for washing her clothes or for the other expenses is if you were negligent and caused the bird mites to spread into her unit or something you did as the landlord (or failed to do) caused the mites to spread into her unit. If she can demonstrate that the bird nest is the source of the mites and you had a responsibility to clear the bird nest, then you could be held responsible; however, the ability of her to prove that is highly doubtful.
Since she would be the one suing you for reimbursement of her expenses, she would have to carry the burden of proof. Sounds like that would not be a possibility.