During the 30 day written notice; can a landlord show the house while still occupied by tenant during the last 30 days of occupancy ?

Depends on at least two things:

1. which state or country the house is in
2. what, if anything, the lease (if there is a lease), says about it.

Has the tenant given written notice of intent not to continue to occupy the premises; or the landlord given written notice to quit?

Thanks... got answer to information needed.