Your mother is right in showing reluctance to bow to the repentance. If she feels that strongly about it then please do not go against her wishes.
You could go outside and bow to Shakyamuni Buddha 10,000 times too. Great Master Xuan Hua used to bow outside of his parents’ house too.
Personally, I feel that it’s more important for our mind to be most respectful when bowing. In that case, the environment bears little consequences: you are not creating offenses at all. In contrast, people who bow to the Buddhas in the most adorned Buddha Halls and yet fail to be respectful are in worse shape.