بسم الله الرحمن الرحيم
It is lawful to read the verse number 74 of Surah al-Furqan (رَبَّنَا هَبْ لَنَا مِنْ أَزْوَاجِنَا وَذُرِّيَّاتِنَا قُرَّةَ أَعْيُنٍ وَاجْعَلْنَا لِلْمُتَّقِينَ إِمَاماً) in Qa’dah Akhirah (last sitting of Salah) after reciting Tashahhud.
One can read any dua mentioned in the Holy Quran and Hadith in the last Qa’dah of any salah after tashahhud. However, it is better to read those duas which are prescribed for these times and it is not correct for the Imam to read very long dua.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.