It is very difficult for widows to financially support themselves if they have children to look after. This problem is aggravated in countries which do not offer any support to them. By sponsoring a widow and her children, you can ameliorate their difficulties by covering their basic needs.
The Islamic ruling is that after the husband, the responsibility of her assistance and maintenance falls on the son, father, and brother(s) respectively. Failing that, the responsibility falls on the community around her. Failing that the responsibility is on the Muslims as a whole.
For those without the means or ability to earn a living, poverty is a life sentence. Al-Hikma Foundation works to improve the situation of vulnerable widows by providing financial support, food, clothing and housing.