Is it permissible for a husband to take from his deceased wife's money, which is designated for her children, in order to enable his daughter to go for Umrah with her maternal aunts and maternal uncle?

If these salaries are due to the wife as savings from her salary, then they are an inheritance to be divided among the heirs according to Islamic law. You may spend your share of it on the daughter's 'Umrah. As for the daughter's share, you are not permitted to spend from it on her 'Umrah unless you fear for her loss due to her not accompanying her aunt.

If the salaries are a gift from the state to the children without specifying each one's share, then you may spend from them on the daughter's 'Umrah if it is in her interest. However, if the state has specified each child's share, then you are not permitted to take from another's money or spend her share on anything other than what the granting authority has specified.