Mahr

Q: If during the nikah, the wife gave the groom a specified amount of time to give the dowry. Example: The wife gave the groom till August 28th to give Dowry of $300. Since then the groom has put the money into a non-interest savings but the couple needed to take from the savings to make ends meet. The total amount put into savings exceeds the $300 dowry. Is the marriage still valid if $300 isn't given to the bride by august 28th?

Q: If a wife passed away mahar wasn't paid to her than what should husband do now? Is it still to be paid? If yes then to whom should it be paid to?