A typical canonization process will take several decades to conclude, and many saints who are canonized lived a long adult life. This means that the possibility of a parent attending a canonization ceremony of a child is extremely rare.
Furthermore, even when it takes only a few years for an individual to be canonized, historical records don't always point out who was present at the ceremony. (Keep in mind for the first several centuries of the Church, there wasn't a formal canonization process.)
For example, St. Peter Verona is known as the saint who had the fastest canonization. He was canonized after his death at age 46. It's possible his parents were present at his canonization, if there was a formal ceremony held at that time. Yet, we don't know his parents' names and the only detail we are given is that they were adherents to a Manichaean heresy at the time. They were probably not happy with their son's canonization, if they were alive.
When speaking of fathers being present at a canonization, we also run into the fact that on average, men die sooner than women, especially since men were often soldiers, or were exposed to various diseases in their work.
This was the case for St. Aloysius Gonzaga who was beatified in 1605, but his dad died in 1586. Also, St. Maria Goretti was canonized in 1950, but her dad only lived until 1900, when he died of malaria. (Her mom was at her canonization though!)
With all of this in mind, we can assert that the following two saints had fathers alive when they were canonized.
St. Anthony of Padua
One of the fastest canonization on record was St. Anthony of Padua, who was canonized a year after his death. St. Anthony was also relatively young when he died, being 35 years old. His father, Martin de Bouillon, came from a very prominent family and it is likely that he was alive when his son was canonized. He is mentioned several times in biographies of St. Anthony, proving that he was alive during his son's life as an adult. We don't have a historical account of the canonization that includes a list of attendance, but based on the evidence we have it appears likely.
St. Carlo Acutis
Both of St. Carlo Acutis' parents, Antonia Salzano and Andrea Acutis, were present at the canonization ceremony of their son. Andrea is the only recorded father to be present at a canonization ceremony, at least in the modern age.
