I read thru all of this and it seems it has snowballed. First lets look at the facts. You may want to write them down in a notebook and keep a dated diary as things transpire. Make sure none of the pages get torn out, and not a spiral.
1. Revoke the poa the grandaughter has. Drive mom to an attorney and walk her in let her to do it on her own. you can set up the appointment, but let her do it.
2. Make a second appointment soon after or on the same day giving you poa.
3. I must agree putting the house in your name is an excellent idea, avoid the cost of probate. You do have another choice, you can put it into a trust with your name only as benificiary. No one else cazn touch it, however it has to be in your name for X amount of years before she passes or it is null and void and can be contested. If she has at least 3 to 5 years left, I would say you are safe. Nasty business this.
4. Definately have Mom set up a nice public dinner and invite not only your greddy siblings, but Moms sister, brothers, cousins, friends who know her wishes and that yoou take care of her. so you and your Mom have support at this dinner and the siblings are not likely to make so much of a scene. Bring revoking poa paperwork, your new paperwork as you the poa, and let Mom tell them in her own words her plans to live out her golden years at home. She worked hard for her home and it is her decision to will as she wants. She could go as far as to inform them she is ashamed of thier bad behavior and raised them better than to act like vulchers. She needs to be clear without getting upset. Deliver all with a smile and sweetly. She needs to be firm and final with them. Make them aware they will respect her wishes or not come around till they do. To shame them make them aware they are young able bodied and can earn thier own house instead of trying to take hers. She obviously wants you there and wants your care and support.
5. As andded benifit, use the Division of agings visit to your benifit. They have cases of ensure and meals on wheels, and can get you free equipment for her. Make your lives easier, all you do is ask. Make them welcome and on your side.
6. Last thing. This is simple. In everything you do and say make sure you are the guy wearing the WHITE HAT. Be the good guy, the right guy. Ask your self "Am I going to appear to be the guy in the white hat if I do this?" An attorney, who was honest, said he always tried to wear the white hat. To be the good guy. Do not let yourself fall into thier bickering. Make them respect your mother. A gentle reminder of who they are attempting to rob of her golden years would help. Picture albums, memory lane of Mom at her best and all she gave them. Guilt can be a help with greedy children. Yes, invite them to see her, but if they are disrespectful, they need to go home. but make sure they know they can return, but must behave around her. It is so sad to see your children resort to such things.