This is one that a lawyer in your state better answer or there will be hard feelings, or worse.
Generally if a spouse dies without a will the NET assets (after paying off debts) in her name are divided up, according to the state's law of intestate distribution, between the surviving spouse and the children (and children of any pre-deceased children). The first $X (it varies by state, and I do not know what the law is in your state) often goes to the spouse and the rest is divided up like 1/3rd or 1/2 to spouse and balance equally among each kid.
Of course, if and to the extent there was property held in joint tenancy with right of survivorship, that goes to the joint tenant, apart from the will or state laws on intestate distribution, net of any obligations with respect to the property.
In your case if the house was in joint name, subject to a mortgage, it would have passed to your father, subject to the mortgage, and then when you father died, under his will, also subject to the mortgage, to you. What went to your father in terms of other property now goes to you, subject to his deaths.