بسم الله الرحمن الرحيم
In the case mentioned above, when you do not have any fear of life and wealth and you may also perform salah easily in mosque, then you are not allowed to leave jama’at. Therefore, you should convince your mother wisely that no one should obey a person (though parents) by disobeying Allah, as it is mentioned in Hadith:
لا طاعۃ لمخلوق فی معصیۃ الخالق
“None should obey a creature by disobeying the Creator.”
Allah knows Best!
Darul Uloom Deoband