When has a tenant returned possession?

[James Farrel]

Tenant gave proper notice October 20 to end month to month lease November 30 and paid the rent due through the end of the lease.   Tenant stated I could advertise the unit as available to rent November 15 with understanding that any rent paid past the date of a new tenant's lease start date prior to December 1 would be credited back.   Tenant did not begin moving out until November 15  and new tenant lease will not start until December 1 since the tenant never gave me an updated, firm move out date, and I did not want to take any chances.   As of today November  24, tenant has removed everything except a few dumbbell weights which she told me by phone a week ago that she still wants.  Tenant has not been in unit for at least five days and has not returned messages to schedule move out inspection and to arrange to return keys and pick up the weights.

If I do not hear from the tenant before December 1, can I change the locks and let the new tenant move in?   Can I store the weights in case she returns for them?  Alternatively, do I have to file for eviction due to her being a holdover tenant?