Thanks for the responses. I checked with an attorney and was advised that in Maryland the law is vague. Basically, it just states that you need to give "reasonable notice" which the attorney told me is typically interpreted as at least 24 hours documented notice. The lease (which has expired) states that under normal circumstances and if it's not an emergency we need to give a week's written notice. They would be holding over which to me isn't a normal circumstance. Whatever the case, I agree that safety wise it's not a good idea to enter an occupied house plus I wouldn't want to put us in a position where anyone could accuse us of theft.
Yes, if they holdover we will file for eviction. And, yes @Thomas S, I should have made myself more familiar with landlord-tenant laws. For what it's worth, the house was not purchased as a investment property-we lived there for a number of years, needed to move and couldn't sell without losing a lot of money so we've been renting it out. As soon as these tenants leave we will be trying to sell again-I am admittedly not cut out for this business. There are many things I should have done (including not buying the house in the inflated mid 2000's market)-shoulda, woulda, coulda. It's been and continues to be a learning experience.