She has always had anxiety, even as a child she says, but she and my dad traveled quite a bit and now she doesn't want to be away from her house at night for any reason. I try to go and visit as much as possible but it would be so much more satisfying for my family if she were to come to my house and have my children and grandchildren visit there. (She lives almost two hours away)
As long as she's making a little progress here and there, her grieving is not unhealthy and there's no good reason to make her come to your house to make it easier on you. She wants to be where things are familiar, where she feels your dad close be, and where she's comfortable. She may not want anyone to hear her cry at night.
Do you think your mom could be a bit depressed from her husband's death? After my dad's passing, mom's been on an anti-depressant. Hard to tell how much it helps with her memory issues, but it's something to consider.
If she getting out during the day? Do your brother's check on her and visit?
Its only been 6 months and she is 85. She cared for him and now she has no idea what to do with herself and grieving her loss. She wants her own bed.
She is still very early in her grieving, and everyone deals with grief their own way, so for now, just cut your mom some slack and continue to go see her at her home. You can of course continue to make the offer to come stay with you for a while, and hopefully in time, she will. But remember too, that the holidays are the hardest part of the year to get through when you've lost someone dear to you, so be patient and be kind to not only her, but to yourself as well.
I'm sorry for your loss.