[CA] what would you do?

My sister has been dealing with severe mental health issues while starting a new job. We revelry tragically lost a cousin in a car accident, my sisters best friend since birth. She got a "call avoidance" at the insurance place she works (huge company that services almost every state) - she told me it was 5 calls out of thousands; some was tech issues and some she was having panic attacks. She was recently diagnosed with adhd, severe depression, severe anxiety. During panic attacks she would end call or simply not be able to respond, she would take a few mins to take meds and would continue taking calls. She was told of another occurrence, occurs she'll be let go without warning. The manager first told her tier 2, and when my sister asked for a copy of conversation stated it was tied 3 as another manager corrected the mistake. My sister went to HR to voice her concerns, hr listened said "sorry for your loss" and to take it up with her manager. I've never had HR tell me to handle with my manager, they're usually the ones who handles any workplace issues, etc. my sister is asking for advice and l'm not sure what to advise. Clearly find a new job but does she complain about the write up or HR? What would you do if you were in this situation?