We give my MIL lots of attention, gifts, phone calls, do her taxes, Christmas shopping, etc., but she is so volatile. Any ideas?

She was high! Has she been on drugs for years? If so, it explains alot.
Maybe late, but be honest. You and husband have made plans this Christmas. Sorry, but you can't include her. When she rants, be honest that you want to enjoy the holiday and you can't if she is included since previous Xmases have not gone well.

Joy, some elders age gracefully and accept their age.... others have a total meltdown and resent that they can no longer do what they did decades ago. Aging isn't easy.

My Dad aged gracefully and was happy with whatever was going on around him, he kept his sense of humor, his caregivers loved him :)

My Mom was the total opposite, didn't like any caregivers, refused to move from a house with a lot of stairs [she was in her late 90's], and wanted everything her way. I believe the physical issues made her resent aging, she had lost most of her hearing and much of her eyesight. I don't think I would be a happy camper, either, if that was me. I had to remind myself to step into her shoes to understand what she was going through.

As for the short hair cut.... how many of us here ever had that situation happen to us? I did back when I was in my 30's, had my long hair cut into a Dorothy Hamill haircut and was shocked afterwards, I was afraid to go to work the next day :P

What you are going through is not easy. I found the best advice I got from caregivers was to have a sense of humor as that is how professional caregivers handle a person such as your Mom.

lablover64 - your response resonated with me and the situation I'm in.  Your point about cashiers, waitresses, etc who see my mom as a sweet dear frail old lady have no idea.  Also, the care facility folks who ask why such a short visit, or otherwise comment (judge) also have NO idea.

This is why I will NEVER judge someone who is caring for another-ever. If you're not in it, you have no idea what's happening or going on.

My mother is very temperamental, always has been. She was a spoiled only child who always figured someone would look after her and do the mundane chores and conduct her business for her while she did whatever she pleased. First it was my grandparents, then her three husbands, and now it's her three children and one of her five stepchildren. I've noticed that elderly folks seem to become more self centered as they age, so Mom actually has a double dose. She doesn't get that my siblings and I have families and work responsibilities - we're supposed to just hang around by the phone until she needs something and drop everything to rush to her side. I am the one who visits regularly - every week - and takes her out. The rest of the family don't want the bother of hearing her constant complaints about her AL facility, who is "stealing" from her, and all the aches and pains she suffers, nor do they want to deal with incontinence issues and tantrums she often has while in public. Waitresses, cashiers, receptionists - they all beam and say what a sweet little old lady she is. They have NO idea. It's frustrating to suffer an hour of her bad behavior and a verbal tongue lashing and have one of these do-gooders scowl at you and tell you "you should appreciate your mother." Yup, I'd appreciate it if she treated me with some kindness and respect just because I'm her daughter - forget all the stuff I do for her. One day I couldn't take any more and told her "If you're going to treat me like this when I am the one who visits you and does errands for you and takes you out for dinner, then I guess I better call once every six months and see you only on your birthday, Mother's Day and Christmas like the rest do - they don't take any abuse and you always seem glad to see them." That got her attention, even with the dementia. She realized that I'm not obligated to do what I do for her, I do it out of kindness and I could just as easily make myself scarce like the rest of the family does. She has backed off on the abuse since then.

You obviously cannot treat her like she’s “normal” be it from dementia or a life of things going exactly her way with no resistance and unquestioning obedience, she’s far from. My mother was ungrateful as well. 90% of the gifts I gave her were returned to me for some flimsy reason. My son once sent her a beautiful bouquet of flowers for her birthday and she was practically beside herself with dismay and ingratitude. She insisted I take them home. I refused. When I visited a few days later, the flowers were plopped on a table in her apartment lobby—out of her sight. I was furious and told my son to not send her flowers or any gift ever again.

You can’t change her. You need to change yourself. If you stand directly in front of someone who’s swinging a baseball bat around, chances are you’re going to get hit. So stand aside. If she’s an addict, speak with her doctor. My mother was on an anti-diarrheal medication that was an opiate. She was hooked on that to the point it affected her entire gastric system. Stand back. Enjoy your family and celebrations without her.

At the age of 92 she's not likely to change now especially since you say she's always been like this so all you can do is try to preserve your own sanity and patience. Maybe don't go so out of your way to do things for her if your reward is toxic, volatile, ungrateful behavior from her. It's OK to back off a bit.