They were on the train, the inquest found a problem with the sleepers which caused the train to derail, several carriages ended up on their sides, the coroner found the driver was not to blame but said he was determined to issue warrants for the arrest of a list of people ( mainly railway directors) for manslaughter due to the condition of the sleepers, hence the cert statement of homicidal.
I thought you might want this bit
Irish Examiner Sept 10 1878
Mrs Mary Brew was than sworn. She said “I live at No.1 Connoll’s Alley Hanover Street. I am widow of the deceased Michael Brew. I saw the body today and identified it as my husband. He left me yesterday morning at 10 o clock to go to Kilcrea to my father, and he was to return home by the Macroom train in the evening.
Thomas Murphy was travelling with him. It appears they went fairly often to visit Mary’s father.