Suggestions here have generally been organizing events and speeches, but of course, you have to do something within the working hours. I would not suggest taking women employees away for dinner or evening because a woman is as much an important part of the family, and her husband or children would love to spend the evening with her. I would take my wife and children out for dinner, and my children give gifts to their mother in the evening at the dining table.
Organizing Celebrations
If you have any function, let the women organize the celebrations. Let not men intervene and come up with preconceived ideas on celebrations. I liked a suggestion that let women speak on their experience in the workplace. Get somebody to train them for an hour on self-defense. Let somebody counsel them on domestic violence. (At least the working women who are independent, please do not tolerate domestic violence; get out of that marriage.) Get somebody to counsel them on personal finance management.
Appreciating Women's Contributions
A woman is the most beautiful avatar as a mother, wife, and the most underestimated leader. Do anything to appreciate their contribution to the company but also family and society as a whole. PLEASE DO NOT MISTREAT them. They deserve more but get very less.