Fornication -- sex between an unmarried man and unmarried woman -- is not a mortal sin.
Every priest that I have known would not deny someone the Eucharist if someone stepped forward to receive the Eucharist.
No priest would make a spectle out of denying anyone the Eucharist at a mass.
The sacraments, including the Eucharist, are to be comforts to those who believe.
Denying someone the Eucharist at a funeral mass does not follow that element of Roman Catholic doctrine.
Personally, I don't like the heavy black, including the veils. I find it overboard -- more worried about the look than the grief.
Personally, I never wear complete black to a funeral.
I wore black slacks & a pistachio sweater to my sister's funeral and I wore a navy blue skirt & a brightly striped sweater to my father's funeral.
(both were Roman Catholic masses)
I am sorry for this loss to all the family and the people of Monaco.