Claim of legal heirs in bank accounts where no nominee mentioned

Husband died without mentioning the name of a nominee, either his surviving wife or two daughters, in two of his bank accounts and few share holdings. Rest of his bank accounts and property has his wife's name as nominee. Two sons of the deceased elder brother have submitted their claim in the said bank accounts and shares. Is this valid ? If not, how to proceed in the matter so that the property goes to the rightful inheritors ?