I wonder if she is feeling pain somewhere and thinks she MUST have fallen.     See if you can approach the subject like, "Mom, do you have pain anywhere?   Does anything hurt?"

It's easy to be or get confused, I do now almost daily and my wife will tell me "I already told you that an hour ago now put your clothes on and lets go or we will be very late.... I'm only hurting in my left leg thigh and hope I don't have to get it operated on like the right one was done back in September...

Everything seems back to normal now. I am getting supper ready for us. She thinks I am a different person than the one she wanted to fight with earlier. I'll accept that if it makes things better.