Answer:
The question says:
Why the narrator uses the word "mujercillas" instead of "mujeres (women)"
the end segment -cillas is a diminutive, in this context, this diminutive is used to say that those women are not "women enough" because they liked "non-clerical things", "being seen by others" and things that he tinked were "bad" for women in the time (things that a "lady" do not do).
"La usa para decir que esas mujeres no son"suficientemente mujer" porque hacian cosas que el consideraba que no eran para una "dama""