I would let her know that due to her behavior you are not willing to meet her in person but you will hang her daughters items in a bag from the mailbox on x day from XX-XXpm. Make it a time that your husband is home and avoid that area of the house during that time so you won't see her. Let her know that after that time if the items remain they will be disposed of.

Don't let this bad experience prevent you from providing future care. There are many respectful families out there that will treat you appropriately.