Her husband was killed in the Madrid bombings. From Expatica, with thanks to Sr. Soph:
MADRID — The widow of a man killed in the Madrid bombings attended the trial of Islamic radicals with a cartoon of the prophet Mohammed with a bomb on her T-shirt….
The T-shirt was a copy of the cartoons showing Mohammed on top of a bomb which were first printed by a Danish magazine and which caused disturbances in Muslim countries around the world.
I suspect it is actually the one with a bomb on top of Muhammad, that is, a bomb in his turban.
The judge decided the woman was free to wear what she liked and could come back to the court if she wished.
The woman, who was not identified, is a member of the Association of those Affected by Terrorism.