Is it normal for my elderly mother who is 78 to be stuck in her own "bubble" and think the world revolves around her and her opinions?

My mom was widowed about 2 1/2 years ago . I first noticed her anxiety when she was caretaking her husband (my stepfather). She had two major breakdowns at that time. I was able to calm her down, but was a bit scary to watch. After he passed, she got VERY anxious which I would assume is pretty normal, however I have never known my mom to be anything other than a strong person. I encouraged her to get some help via a grief counselor, dr, etc.. however she refused. She refuses to take any medication at all which is understandable as she is generally very healthy. I do think counseling would be very helpful, however pretty sure it's not going to happen.
She lives by herself, about a mile away from my husband and I. She is perfectly capable of taking care of herself on a daily basis so this is not the issue at all. She comes up 4-5 nights a week for dinner so she doesn't have to eat by herself and watches movies with us.
The best way I can describe her anxiety episodes is a Deer in the headlights look, confused and shaky. She starts to snowball when she starts getting anxious about something. I can usually talk her down and tell her to breath, but if she is by herself, she gets confused and it takes awhile to get over it. The other part of the issue is she has VERY harsh reaction to small things. She has NO filter and has hurt my grown children's feelings more than once with her words. Such as.... It's about time you disciplined him! (talking about a 3 year old). But yelling at my son. Seems almost angry that people cant take the truth as she sees it. She has made several comments about having to not voice her opinion as it may hurt someone's feelings according to me. I have tried to have a calm discussion with her about just blurting out what she's thinking instead of thinking about it before it comes out. She has distanced one of her granddaughters for this very reason.
I think it would be easier to understand if she had always been this way.. BUT this is a person I don't know. My mom and I have been very close my whole life, but the person I see in front of me is a whole different person. It's sad and I am watching my children, her grandchildren backing away because of it and it's heart breaking. It's like she's walking around being a ticking time bomb. I used to be able to sit and talk to her and confide in her about anything, but now I would never do that due to the reactions and judgements.
Any suggestions would be appreciated as I am feeling more stressed each day.

When did this self-centered behavior begin? In the past few months? When she turned 75? When her husband died (if applicable)? You don't know when it started because she has always been like this? Some perspective on the history of this behavior might help.

I think it is often "normal" (though annoying for others) to become self-centered during an illness. And some days getting old can feel like an illness! Does this mostly happen when your mom is "under the weather?"

Your profile says Mom has anxiety. How is that being treated? How long has it been since a doctor has evaluated and adjusted her treatment plan?

What is the nature of your caregiving? Do you live together? Talk to her on the phone everyday? Visit twice a week? What kind of care does she need? Can she plan and make her own meals? Pay bills? How do you help her during anxiety episodes?

What you are facing is "common," if not "normal." Give us a little more background and others who have had/are having this experience can share their coping methods with you.