All praise be to Allah, Lord of the Worlds and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
In all situations, it is better to join the congregation at the mosque, then return home and lead your household in prayer so that they receive the reward of the congregation. It is stated: "If he can join the congregation at the mosque and return home to lead his household in prayer, then this is better." {Al-Hashiyah Ala Tohfat Al-Mohtaj, vol.2/pp.252}.
If this was hard to do, then it is better that you obey your mother at the times in which she asks you to lead her in prayer, and doing so, Insha`Allah, doesn`t mean losing the reward of the congregational prayer at the mosque. Our eminent scholars (May Allah have mercy on them) said that your household`s receiving the reward of the congregation is due to your leading them in prayer. In this regard, It is stated: "It`s reward could be equal to or even more than the reward of the congregation at the mosque." {Al-Hashiyah Ala Tohfat Al-Mohtajj, vol.2/pp.252}. This is in addition to the great reward that you will receive for being dutiful to you mother. And Allah Knows Best.