My father passed away and was leasing a house in Arizona. The death clause in the lease states that upon a death the heirs are allowed into the premises to recover any propery of the leasee. There is nothing in it about the heirs being responsible for the lease, only that we can get into the house to get the property. The landlord is saying this is a breach of contract and is keeping the security deposit. Is this leagal?

The heirs are not responsible for any unpaid rent on the aparatment, but the estate is. The executor of your father's estate should contact the landlord and pay off whatever money is rightfully owed, using your father's assets.