Does the wife deserve a share of the endowment dedicated to the grandchildren of the endower and their descendants, noting that she married the father one year before his death, did not bear him any children, and her 'iddah period from him ended, whereupon she married and gave birth to a child immediately after the husband's death?

Waqf is the endowment of an asset and the dedication of its usufruct for the sake of reward, and it is among the acts of devotion whose reward does not cease after death.

If your paternal grandmother endowed a waqf for her grandchildren and their descendants, then your father has a right in it, being one of the grandchildren. As for your father's wife, she does not inherit from this waqf, because she is not among the grandchildren nor their descendants, and this is based on the condition set by the endower.

Matters of inheritance are serious and must be referred to the Sharia (definition) courts for investigation, as wills, debts, or other rights may emerge that take precedence over the heirs' rights.