Answered by: Mufti Javed Ibn Nazir Kachhalia
What is the ruling regarding wishing someone a happy women’s day?
In the name of Allah, the Most Gracious, the Most Merciful
Islam teaches us that we should be appreciating the work of our mothers and sisters throughout our life.
Celebrating special occasions such as mother’s day, father’s day, women’s day, etc., doesn’t have any basis in our religion, therefore, we should be adhering to the Practice of our Beloved Prophet ﷺ.
A hadith has been narrated:
by Abdullah ibn Umar: The Prophet (ﷺ) said: He who copies any people is one of them. 
Celebrating occasions that haven’t been practised by The Prophet (ﷺ) or the Companions are not something that has been applauded and celebrated by Shariah on specific days or occasions.
Rather, Islam and Shariah have taught and shown us the importance of women our entire life.
If she is a mother, the hadith says:
Abu Huraira reported that a person said: Allah’s Messenger, who amongst the people is most deserving of my good treatment? He said: Your mother, again your mother, again your mother, then your father, then your nearest relatives according to the order (of nearness). 
If she is a sister or a daughter, the hadith says:
Abu Sa’eed Al-Khudri narrated that: the Messenger of Allah said: “Whoever has three daughters, or three sisters, or two daughters, or two sisters and he keeps good company with them and fears Allah regarding them, then Paradise is for him. 
Only Allah knows best.
Written by Mufti Javed Ibn Nazir Kachhalia
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Sunan Abi Dawood
 Sahih Muslim
 Sunan At-Tirmidhi