They're upset because a young woman who was visiting the city with her family was arrested by the "morality police" (this is the English translation for what they are called, it is a police force that looks for women not dressed properly and brings them to a detention center where they are "re-educated" and forced to swear to never again wear their hijab improperly), and while her family waited outside the center, she was killed. Or rather, she was taken to a hospital and pronounced dead shortly after. The official claim is that she collapsed and died of a heart attack but she was in her early 20s and healthy, and it's far from the first time women have been harmed in this way. For the women of Iran, this is the reality of life. Most of them have either been taken there at some point, or know someone who has been. There are a great many accounts of abuses perpetrated at this place. This particular young woman who died was actually wearing her hijab, she was arrested because it wasn't being worn "properly". The younger generation of women wants to have the choice in how they dress, many of them are fine with the hijab, but many of them find it a symbol of oppression. It's a more complex situation than it is in Afghanistan, where women are not allowed out of the home once they reach sexual maturity, and are not allowed to work or be educated beyond grade school. There, a woman can be legally stoned to death for not properly wearing the hijab. In Iran, women are allowed to be fully educated and there are women surgeons, lawyers, etc. Women are represented across all areas of life, but a woman's husband can decide for her whether or not she can work, and there are no protections against domestic abuse or sexual violence (not just from their husbands but from anyone). So women are doing better in Iran than in many areas that have fallen victim to the fundamentalist wave of islamic states that has taken over much of the muslim world in the past 4 to 5 decades, but the situation is still not good.