Final answer:
The most comforting euphemism for the word 'death' among the options is 'passed away'.
Step-by-step explanation:
The most comforting euphemism for the word 'death' among the given options would be 'passed away'. This phrase is commonly used to soften the impact of the word and make it less harsh. It is a gentle way of referring to someone's death.
Another euphemism, 'kicked the bucket', is a lighthearted and humorous expression, but it may not be as comforting to a relative in a serious context.
The phrases 'bought the farm' and 'is sleeping with the fishes' both have negative connotations and imply a violent or sudden death, making them less comforting choices for a relative.
Learn more about euphemisms for the word death