Tribunals PIP for mental health

Hi my daughter is 27 and was on enhanced rate pip for 3 years she recently had her medical and got 0 points on anything. She has had low mood since 2011, anxiety and suicidal ideation since 2016, and a psychiatry diagnosis off severe depression with psychotic symptoms. She finds it very difficult to get out the house and her GP usually rings her rather then her having to go to her doctors. She has recently been referred back to the community mental health team due to the severity of her mental health this is all stated in a support letter from her GP. She is om citalopram for her mood and rencently got put on diazepam as shes started picking her sick uncontrollably. She has a history of self harm which she hasnt done in a year but all this stress she has to use things she learnt off her mental health team to stop her she said she has an overwhelming feeling on a daily basis to self harm. She has recieved a letter off tribunals service saying "if you wish to attend a hearing" so im wondering if this is a good sign or should we attend to put her case across. Since november her mental health has gone down hill and needs another assessment to see if there is anything else going on with her. Any advice would be great as weve never done this before. 

Thank you