In my opinion, W4 is entitled to an equal share of her husband’s properties like other surviving, entitled heirs. Under Hindu Succession Act, 1956, the properties of a Hindu male dying intestate devolve, in the first instance, equally on his sons, daughters, widow and mother.
If the ancestral property was partitioned and a share thereof devolved upon the widow according to this partition, the said property became her self-acquired property. W4 has full right to inherit the entire property of her deceased husband.
W4 having no legal heir can write a will, gift or sell the said property at her discretion.
Hope this helps.