It doesn't matter wether the marriage occurred in the DR or the US, or where any of the spouses where at the time of death. Real Estate Properties are solely governed by Dominican Law.
If spouses were married under community property rules, which is the norm in the DR, it is irrelevant in whose name the property was titled, it belongs to the matrimonial community, and in case of the death of a spouse, the 50% beloging to the deceased spouse goes to his or her heirs. (assuming the property was purchased during marriage since property acquired by a spouse before marriage is not community property).The other 50% will belong to the surviving spouse.
The 50% the estate must go to the children irrespective of the existence of a will ("forced heirship"). For example, in a estate with three children, at least 75% of the estate must be reserved for the children (Art. 913 of the Civil Code).