Thank you for your question. I hope you don't mind if I write my answer in English.
Your mother appears to have a memory problem which is more than expected from her age. This could be an indication of an abnormality of brain function. There are several possible reasons, such as early degeneration of brain cells or other lesions in the brain, a vitamin deficiency, or a thyroid hormone deficiency.
The best thing to do is to bring her to consult a neurologist ( a specialist in the nervous system). The specialist would take a more detailed history of her symptoms, perform a thorough neurological examination and order appropriate tests to try to find the cause of her memory problem so that she can be treated properly.