My mother does the same things, she prays over 100 times a day, and tells people that i never fed her or care about her. She also has sun down by 7pm she packs all her stuff and ready to leave, when I tell her she can't leave she threatens to call the police.
That is exactly how my mother was. My suggestion is, when she gets ready to leave, try and distract her. Tell her something like, give me a few minutes and I will drive you. Or let me finish what I am doing, and I will take you. Or let us wait until so and so comes, and we will go together.
