My grandmother has lost it (long concerned rant)

My grandmother is my best friend. Always has been. She's a young grandmother and we do almost everything together, whenever im with my mom we are with her and I'm usually around her more than my mom. With that being said, for some reason around this time of year she goes off the wall. My mom called me and asked what the hell I did to her yesterday (I was at work so Idk?) Said my grandmother told her I was so rude to her (because I said I didn't need any help wrapping presents)...and then my grandmother went off on my mom about how she just gets in everyone's way and how she'll just stay home and not bother anyone because we all have a better time without her. And how my mom never sees her anymore (they are with each other literally every weekend and when I'm not working I'm with them too). And then she even brought up things that happened years ago with my mom and how she's upset that she was invited to our cousin's Christmas party...like...what? And then she basically hung up on my mom.

And so now I'm stressed because I seriously have no idea what just happened. My mom is going to call her back sometime today. I think my grandmother reads texts as how someone would speak them?

But again it's stressing me out big time and my face gets really red and I just don't understand where any of this is coming from. Everything she went off on my mom about is not true at all. I know that she got jealous of me and my husband when I got married....because I was married and apparently had no time for her... And now the baby is coming soon and she thinks I'll definitely no longer want her around. Again, all of this is so not true, have I gone a 2 weeks without seeing her? Yes. But I talk to her EVERY DAY. She did something like this last year too so Idk.. but it's stressing me out and pissing me off. Baby is supposed to be here in a few weeks and if she's gonna act like this I swear...