How can one console a person suffering due to their family's indifference to the sins they commit, despite their attempts to advise them, and who feels enraged and depressed by their coldness?

Allah Almighty does not let the reward and recompense of those who do good deeds go to waste. Rather, He multiplies the reward many times over, as He states: "Indeed, I do not allow to be lost the work of [any] worker among you, whether male or female" (Al-Imran: 195), and His saying: "Whoever comes with a good deed will have ten times the like thereof." Righteous deeds are from the grace and success granted by Allah, and one should be thankful for them and strive in inviting others to Him. As for the aversion of family and the estrangement of the داعية (caller to Islam), this is a trial that distinguishes the sincere believer.