please help me answer this before 10pm

Thank you.

Tom died this year in September. Tom lives in Texas and is unmarried. His income prior to death totaled $50,000. Tom named his sister, Sally, as the executor of his estate. Tom will be due a refund. a who must file Tom's last tax return? b. How is the final tax return signed? c. Who collects Tom's tax refund? d. How is the refund collected (i.e. is there a form that needs to be filed)? e. If Tom was married and was survived by a spouse, how would your answers to a-d above change? Please include primary authority to support your answers above. This can (and should) include Code, Regulations, Cases, and Chief Council Advice memoranda