According to the New Testament, Lois was the grandmother of Timothy. According to extrabiblical tradition, she was born into the Jewish faith, and later accepted Christianity along with her daughter Eunice.
Her only biblical mention is in 2 Timothy 1:5, where the author tells Timothy
I am reminded of your sincere faith, a faith that dwelt first in your grandmother Lois and your mother Eunice and now, I am sure, dwells in you as well.
–Wikipedia