Frustrated daughter-in-law/caregiver

My mother-in-law has vascular dementia; she lives alone in her own home with upstairs and basement. She has 2 sons who cannot deal well with her care. My husband has had her POA ever since her husband passed away 10 years ago. He recently has filed for guardianship/conservatorship, but has not used his POA to take over her finances or take the steps necessary to get her to stop driving as the physicians have recommended. Her other son lives an hour away but doesn't come to help.  She is on 11 (eleven) meds; we have to take them to her daily. She's been through a "senior assessment" but doesn't grasp or accept the diagnosis, and will not turn over care to us. In ten days we plan to move her to an assisted living facility for 3 weeks while we go away (out of the country) yet my husband still hasn't taken any steps to facilitate this, either with the facility or with her.  She doesn't know anything about this yet. We intend to "place" her there in her own apartment when we return from the trip. My husband refuses to speak with me about the "elephant in the room" and gets angry with me if I bring up the subject.  This "game" has been going on for several months. I frankly question if he should really be her guardian, as he seems not to be able to make the hard decisions. I volunteer 3 afternoons a week at an adult day care center and have learned a lot in past couple years about dementia which helps me direct my husband in steps to take, yet I'm very frustrated at his unwillingness to discuss the situation or take steps more quickly.  I will appreciate any suggestions others can give me with this situation.