I am so sorry for the situation that you are being placed in but it does seem that you want nothing but the best for your Mother in her final days.  A General Power of Attorney does not necessarily give you the right to make decisions regarding your Mother's heath care.  You would need a Health Care Proxy and also a good idea would be a Living Will.  If Mom is still able to go and speak with an attorney I would have one discuss the issues in detail with her and let her decide what to do.  Otherwise, you can petition the court to become her guardian at this point in her life.  Then you would have the options you wish.  Good luck.