Is the aforementioned widow deserving of zakat, and is it permissible to collect zakat for her in a special account without her knowledge to purchase a house for her in the future?

The poor person eligible for zakat (definition) is one who does not find what suffices him and his dependents for the necessities of life for a year, which include food, drink, clothing, shelter, and medicine. Zakat is given to the poor to fulfill their needs and to lift them from poverty to self-sufficiency. No more than a year's sufficiency is given, unless there is a fear of their destitution thereafter. It is permissible to give the poor person from zakat to purchase a dwelling if they do not possess a dwelling sufficient for them and their family, and they are unable to secure one even through rent. The fact that the provider is a volunteer does not prevent giving zakat to the needy, as a volunteer may cease their provision at any time.