If you have a way to contact her, ask her to give you the name of someone else who she could make arrangements with to come pick up the freezer and who is also willing to store it on her behalf.
Ask a city councilor or someone else how you can find out what the legal requirements are in your city about abandoned property, whether you have the right to sell it or dispose of it after a certain amount of time.
You can post a legal notice/small classified ad in the local newspaper that says "Jane Doe needs to come pick up the freezer that is being stored at 1234 Easy Street by (definite date) or it will be considered as abandoned."