Talk to Psychologist on Mental Health

AOA. I want to ask this question on my sisters behalf, she is 19 YO and she is always really negative about life and people her sisters brothers even her mother, she always say negative things about others like i am married so she will say '' tum to khush ho apni life myn hmari koi fikar nai hum kysy hyn etc'' always negative about things, she has no friends i don't know why she say every other girl is not good in her uni college or school, sometimes she says that pta nai us ko kya ho jata hy us k mind myn aik hi bat byth jati hy usy bother krti rehti hy she used to write her diary and literally one just cannot hear her diary for 10 minutes because their is so much negativity about life that no one can handle for more than 10 minutes. we went to a psychologist but that was of no use, what should we do my mother is fed up of her as she lives alone with her she always gives tension to my mother about her studies, exams, colleagues and all.