A. How she acquired the property is so arcane? In case, if she got the property after the demised of her husband without a will, in the presence of major children, you need to take the child's consent or must mention in the Sale Deed. Perhaps, in the presence of the minor, she must take court permission to sell the property because of minor interest vested with this property.
B. Sometimes, the society would transfer the flat in favor of the widow after the demise of husband on the basis of the nominee, it will not create a legal valid title over the property.
C. In the absence of major children, release deed in favor of the widow is mandatory.