You are not capable of dealing with a "hoarder mentality." It is psychological and you can not fix her mind.
The laws for adults...They can "live in a tree" if they want and are not a danger to themselves or others. Hoarders can function with past abilities and do that without being a danger to themselves. Consult with a Adult Protective Service Investigator and he will give you a "picture" of what can be done and what you need to do. Remember it is a waste of time in going in and improving or stacking stuff higher...they will fill up ...with stuff.