"The Crimson Horror"
At the end of their adventure, Ada was convinced that a bright young girl such as herself could do well after stepping out of the Dark and into the Light. And the Doctor predicted that she would have a bright future.
I believe that it was not long after she began her new life that Ada found love with a man who could see beyond her scars and blindness. And once married, they began a family.....
This is just a theory of relateeveety, but I believe Ada's granddaughter was named Millie and that she worked at Bletchley Circle during WWII. As far as I can tell, we never learned Millie's last name, but should the series continue and we do learn it, then it could be the same surname as the husband of Ada Gillyflower (which usually means that Millie's father was the son of Ada.)
Rachel Stirling played both Ada Gillyflower and Millie....