Is celebrating Mother's Day permissible or forbidden, knowing that ignoring this occasion might displease the mother?

Righteousness towards the mother and showing kindness to her is an perpetual obligation. Mother's Day is an innovated bid‘ah, and it is not permissible to celebrate it. The anger of mothers does not alter Allah's ruling. Obedience to parents is in what is good and lawful, as "there is no obedience to a created being in disobedience to the Creator." Whatever honor is shown to the mother and gifts are given to her on this day should be done throughout the entire year.