How to deal with a blackmailing manipulative elderly parent?

My mother believes she can still care for herself physically (she can't). Our house recently burnt down - she only survived it because my daughter was there with her. She is homeless and we (my daughter and I) are living in a trailer with only a generator for power - no running water or sewer. This is fine for us as we are healthy and able (relatively speaking) - but my mother is on an oxygen concentrator 100% of the time (or bottles if travelling) - which the generator won't support. She flatly refuses to go into a lodge but has run out of options for where to stay - she's couch surfed through her friends and other family that would have her. As a boundary we've told her that we will not be her fulltime caregiver - she wants someone with her 24x7 (even though she 'can take care of herself'). She's mean - calling my daughter stupid, telling me she should have aborted me. She's abusive - she hit me when I was moving her out of the lodge - a move I didn't like or support but she is still her own decision maker so I was obligated to remove her as I was the 'responsible adult' on file. Per the medical community I did report the incident to the police. She's manipulative and will lie to get what she wants - she was temporarily in a lodge prior to the fire and swore to me that she wouldn't try to make Natalie and I her caregivers - she just had to try to make it on her own at home. When Natalie and I enforced our boundaries (me by bringing her home, making sure she got into the house safely then leaving - I had only agreed to be transport) she got angry because I didn't stick around to feed her (she'd eaten twice while we were out within 5 hours) and convinced I was trying to take control of her - when I was only sticking by the agreement and making her be responsible for herself as she claims to be. She's insistent that she'll buy herself a new house (if she has to sell the farm to do it - which is breaking a promise to myself and my daughter - as we have built a life on the farm being farmers and she promised the farm to Natalie - she's the sole inheritor in the will) but even if she did that still doesn't sort the problem of not being able to care for herself - in the farm house Homecare refused to provide services because she's a hoarder and while everything went up in a puff of smoke - I have no doubt that any place she goes to will quickly become hoarded out. She is complete denial of that as well - and refuses any help. In fact I believe she'll refuse homecare as she did at the lodge because she's afraid that they will discover she's not as competent as she tries to appear - so she pushes them out and leans on us - because we have no authority and she figures no one will believe us (and she's right so far). She has enough in pensions to go into a lodge without a problem and I have said I would supplement her income up to 1000 a month if she would go in. Our biggest problem is even though she isn't rational and flies off the handle with as little provocation as someone disagreeing with her (seriously - not arguing, just disagreeing or saying something she doesn't like) - the medical community says that she only has mild cognative impairment and therefore she is fit to make her own decisions. She's homeless, refuses to move somewhere safe and isn't able to prepare meals for herself etc. I'm so gunshy from asking the medical and social services for help and being told - no - she's still competent - when does she become a danger to herself? I know she's not taking her pills properly and two days ago she tried to claim she could stay on the farm in her truck when she didn't have enough oxygen (spare cylinders). The medical community and social services say that they can only intervene when she becomes a danger to herself or others... Is that now? They keep telling us that it's behavioral not cognitive. We're in Alberta, Canada.