Davies was killed in a mine explosion.

"Davies was killed in a mine explosion. The mine-owners stalled for eighteen months before paying her a miserable pittance by way of a widow's compensation, and it was this delay which drove Mary on to the streets, first in the Tiger Bay region of Cardiff, and later in London." Tom Cullen.
He's made an emphatic statement in his book, Autumn of Terror. 
The gratuity had a moral means:
'Any free member ... who may by losing a limb, or having one disabled by accident or otherwise, or through blindness, imperfect vision, apoplexy, epilepsy or paralysis, be rendered permanently unable to follow any of the branches of the trade ... (provided such was not the result of intemperance or other improper conduct), shall receive the sum of £100 on the production to the Executive Council of satisfactory medical and other testimony of such permanent disablement.
Finally, the union offered members a funeral benefit, which provided ten pounds on their death. Five pounds was paid on the death of their wife. The aim was not to assist the dependents of a dead member, but to ensure that members received a proper burial and wake. The only provision for widows and orphans was a separate discretionary Benevolent Fund, funded from special levies.'
It would appear Mary Kelly lacked moral (Victorian) standards, if indeed Tom Cullen's assertion is correct.