I would like to know if it is safe for a single women to travel in Paris at this time by herself?
Well of course it is. Thousands and thousands of us single women, even those who live here, travel by ourselves all the time though not at 3 am drunk sporting Rolex watches and diamond rings with big bills hanging out of our pockets. Paris is just another big city where city smarts apply although on average and in general it's probably safer than many other big cities.
Assume you had some reservations. It might help if you could articulate some of your concerns. The question of safety is always a relative question.
I am an old lady who has traveled on the metro from one end of Paris to the other at midnight and who always walks after dark -- not at 2 am, but it would be rare that I not be out occasionally alone at 10 pm. I have stayed in about half the arrondissements -- sometimes centrally and sometimes at the edges of Paris. I have never felt unsafe when out and about alone. A young attractive women may attract attention as she night anywhere, but I haven't noticed a lot of aggressive attention. When traveling in Italy with my daughter we had some of that, but not in Paris.
Nobody will jump out of an alley or Metro station, unless you have had too much to drink.
Just watch your valuables - smartphone included - and you will be fine.
My daughter is currently in Paris and has been there for a month. She says she feels perfectly safe, much more so than in downtown Denver.