If a woman dies, having no children, and leaves behind a husband and the children of her siblings (male and female), who are the heirs? And if the husband is not present and the only heirs are the children of her siblings, do the females among them have a share in the inheritance?

Sisters' daughters have no share in the inheritance because they are not among the Quranic heirs (Ashab al-Fara'id). What remains after the Quranic heirs is given to the closest male relative, according to the Prophet's (PBUH) saying: "Give the prescribed shares to those entitled to them; then whatever remains is for the closest male relative." Inheritance cases must be submitted to the Sharia (definition) courts to verify all heirs, wills, debts, and rights before dividing the estate.