In conjuring this thing from the past, for those of us who remember it for having lived it, there were indeed in some cultures (mine included) with customs regarding how to dress and the different stages of life of a woman and what was “expected” and what was showing “propriety”…for all situations.
These conventions could be, as you have discovered, quite ferociously clung to by certain individuals of such generations. My mother and grandmother, who have been gone so long they would have to be one, two or three generations removed from your older friend, were the polar opposite. They did not wear a mantilla ever…although my mother owned one or had been given one; she and her mother used other head-covering. Even after my grandmother was a widow.
Certainly they would never have used the verb “to veil.” It was just not a term used for laywomen. Nuns and Sisters wore wimples and they wore veils. The colour and the length and the cut would have their own meanings…novices wore one colour of veil and professed wore a different colour, for example…those in temporary vows could have one length of veil while those in perpetual vows could have a different length. Or else the veils would have some other modification that gave these indications. All this was determined by their order/congregation.
On the other hand from your friend there were those who, far from clinging to that tradition, flung those conventions as far as possible, and with exuberance, at the first opportunity. My mother and grandmother were of that number. Literally. I remember when my mother abandoned the practice…and she did so with profound satisfaction and no looking back. She had no use for it.
These mores were much more cultural than ecclesiastical. They certainly shouldn’t have any significance at all in the 21st century…since you have Carmel in your name, you could wear the colour of the Carmelite habit, if you were of a mind to do so. You can quite legitimately wear black.
The use of mourning and the hanging of Victorian bunting, with all its prescriptions and meanings, was set aside long before the last of even the Victorians had died.