Sorry to hear about your mother. If you find out what county she lived in and call them, tell them the address and they should be able to tell you what happened to the house. Or you can email or call me and I will be glad to do it for you.
If the house was foreclosed upon, then your only option if you want the house back is to offer to buy it.
Here are the county phone numbers in Denver.
Denver County: 720-913-1311
Douglas Conty: 303-660-7417
Jefferson County: 303-279-6511
Douglas County: 303.660.7400
Let me know if I can help. Ethan