First off I’m terribly sorry for your loss. While I am by no means a paramedic I took first aid classes from one and this very subject came up (what to do with used PPE and such after an incident). We were told to just leave it pending hazmat-trained folks responding for cleanup. At a patient’s home it’s left and frankly not their responsibility - the patient alone is.
Sucks but they will indeed leave stuff behind - I wish it had been a better outcome for your family but I assure you they meant no offense or harm.