My mom 89, had severe dementia and was yelling out. Hospice, nurs. Home and state tried morphine in case she was in pain. 1/5 of a tsp every 2 hours as needed. 2 days later she died is morph. Cause?

Morphine. Morphine is often used for respiratory distress and agitation from lack of oxygen in a terminal disease. It is difficult to answer your question because the amount and frequency of the morphine dosing during this time period is not provided in your question. I would discuss your concerns with the medical provider so you can gain understanding and closure from your loss.
Most likely not. It sounds like your mom may have had delirium at end-of-life. This may be secondary to physical pain, psych or spiritual pain or other cause we will never know. We usually use an anti-psychotic in this situation, I have used morphine if I felt it was related to pain. She was prob transitioning to the active stages of dying and she died from her dz not the morphine. It was to assure comfort only.
Unlikely. This is difficult to answer without knowing the strength of the syrup- 1/5 tsp could have anywhere from 1 to 20 mg of morphine. But it is highly unlikely that this caused her death. Hopefully they gave her a conservative dose. One has to take quite a bit of morphine to overdose. It sounds like she was close to death and morphine hopefully eased her suffering towards the end. My condolences to you.