Why didn't the police show up at the hospital?

Even if suicide attempts were not illegal in that state, and even if the drugs she took were legally prescribed to her, the police would still be called - by the hospital - to investigate. They would have interviewed the son and mother, in order to determine if she should be EPC-ed (emergency protective custody, mental triage, possible short-term commitment, for her own protection, as well as the protection of others in her home). He wouldn't just have an attractive young nurse counsel him.