This is the Death Certificate of Mathilda (Bridget, also Tillie) McCabe-Klinzing. A posting in the Pittsburgh Daily Post on 27 Dec 1917 mentions the accidental death of "Mathilda Klinzing (nee McCabe)" which occured on the 24th.

Below is the text from a newspaper article from the Oakland Tribune California 1917-12-24 about the streetcar crash that killed Mathilda among others. This was originally posted on Ancestry.com April 28th, 2008 by Stu Beitler.

Pittsburg, PA Terrible Street Car Accident, Dec 1917

17 DIE IN STREET CAR ACCIDENT.

Pittsburg, Dec. 24. -- Seventeen persons were killed outright, half a score fatally injured and nearly forty others seriously hurt at the Water and Carson streets station today, when a Knoxville trolley car jumped the track at the south end of the Mount Washington tunnel and crashed into the station filled with Christmas shoppers. Refusal of the brakes to work is given as the cause of the accident.
The accident occurred during a busy period of the day. The car itself was crowded and was bound for the downtown section of the city with scores of women and children, intent of their late-hour shopping inside. While coming down the grade in the tunnel the brakes suddenly let go, and despite the efforts of the crew started down toward the station at a terrific pace.
While women screamed and shrieked in terror, the juggernaut roared down the incline. The Water street station stands at the city end of the tunnel. The station platform was crowded with shoppers and many more were inside the station. A great number of these were children, en route to local department stores to see Santa Claus. While they stood laughing and chatting and making plans for the morrow the trolley car suddenly crashed out of the tunnel.
Scores stood panic-stricken. There are several switches at the station intersection and one of these is supposed to have thrown the car from the rails. Before a single person could make a move to avoid the impending disaster the hurtling car jumped the track, crashed through the human barrier that opposed its flight, tore its way through the station platform and smashed into an embankment. Woman and children were crushed like flies.

Oakland Tribune California 1917-12-24