Is it permissible to financially assist an unveiled sister with her study expenses?

The hijab is an obligation upon the Muslim woman, and she must adhere to it. Advising her with kindness and supplicating for her guidance is a righteous deed. There is no harm in helping her with her study expenses, as long as the field of study is not forbidden, or it is not highly probable that she will use it for something forbidden. However, if shunning her or cutting off her expenses would deter her from displaying herself immodestly, then do so.