After death provisions

Kiindly let me know whether legal representative and legal heirs are one and the same. Please also explain the term 'Representative Assessee'.

Please solve the following also - One of the spouse dies in the middle of the F.Y by leaving all her estate to her husband without considering her children,by way of will. How to file the return :-

Option 1 - All of her income for the FY 2012-13 disclosed in her name and return filed  by her husband on her behalf,

Option 2 - Income upto the date of her death is filed by one of her son on her behalf and the balance income after death is included in her husband's return in accordance to her will,

OR

Option 3 - All of her income is aggregated to the income of her husband for the whole  F.Y