This YouTube video talks a lot about the Widow's Son concept in Freemasonry, philosophically and mystically, showing how Gnostic the Masonic Lore can be.
Mystery of the Widow's Son - The Legend of the Craft
But I want to talk a little bit about the Biblical significance of this phrase.
What does it mean to call someone a Widow's Son? Just that the mother was a Widow at the time the statement is made or refers to? Statistically most women outlive men (Miriam died less then a year before Moses even though she was older then by enough to supervise his Basket's journey down the Nile), so there is no shortage of mothers who have been Widows at some point in their life. Or does it mean she was one by the time the son was born? Is the implied dead husband the father or someone else?
Because Joseph doesn't seem to be present in The Gospel narrative after the jump from Jesus being 12 to "about 30", many speculate he must have died by then. Yet The Bible never explicitly tells us that, and never calls Mary a Widow or Jesus the Son of a Widow.
The Widow's Son of Freemasonry is ostensibly supposed to be Hiram the architect of Solomon's Temple (not to be confused with Hiram king of Tyre, called Hirom in my English translation of Josephus quotation of Meander, who recommended this Hiram for that Job).
This Hiram, sometimes called Huram in translations, is the subject of an alleged Bible contradiction. A number of alleged contradictions come from Kings and Chronicles accounts of the same history describing things differently. In this case, Hiram's mother is called both a Widow of Naphtali (in 1 Kings 7:14) and a Daughter of Dan in II Chronicles 2:14. The answer here is simple in my view, she was a Danite by birth, married a man of Naphtali, he died (I suspect they had heirs since there wasn't a Leverite marriage), then she entered a relationship with a man of Tyre (this man of Tyre is never refereed to as her husband) and by him had Hiram/Huram.
The Masonic story of Hiram interests me in how it demonstrates how determined Satan is to contradict The Bible. The Bible says so little about Hiram (What little it says is all in 1 Kings 7 and II Chronicles 2-4.), that it would be easy I feel to write a fictional elaboration on the character without contradicting what little The Bible says, I could write multiple scripts that go in different directions and still each one would not contradict what little The Bible says.
So that the Masonic narrative makes a pretty big blunder I feel must have been on purpose, the people who wrote these rituals were clearly educated men of their time, I do not doubt that they did what research was available to them.
1 Kings 7:40 clearly says Hiram did finish all the work Solomon gave him. The II Chronicles account does not disagree with that. But the Masonic narrative says he died while a key stone had still not been put in place. And this stone becomes known as "The Stone that the Builders rejected" which is a phrase taken from Psalm 118 that The New Testament uses as a Title of Christ.
Josephus in Against Apion Book 1 chapters 17 and 18 quotes two Phoenician Historians, Dius and Meander. Both refer to a person of Tyre who solved problems with Solomon (as Hiram is also described as doing) though there is no clear reference to this person being an Architect. Dius names this person Abdemon, in Meander he's unnamed but called a younger son of Abdemon. It could be this was the name of his father, or another name he went by. I can't help but suspect this name is partly where the Abiff surname for the Masonic Hiram comes from.
Another Biblical figure who could be called a Widow's Son was also a contemporary of Solomon. Jeroboam son of Nebat. 1 Kings 11:26 says his mother's name was Zeruah and that she was a Widow. And another thing these two widow's sons have in common is a connection to Dan, since Jeroboam built one of his two Calfs at Dan. Is it possible that the Masons want to claim descent from Solomon's Temple when they really come from Jeroboam's Temples? Masonry does heavily promote British Israelism, particularly the Orange Lodge.
Another Widow's Son of The Bible would be the Son of the Widow of Zarephath who Elijah rose from The Dead. There is an obscure passage in The Talmud that suggests this Widow's son is Messiah Ben-Joseph, interestingly Jeroboam is also someone a wanna be Messiah Ben-Joseph would seek to identify himself with.
Acts 1 quotes Psalm 109 in reference to Judas Iscariot, that leads to speculation if all of Psalm 109 could be applied to Judas. Verse 9 says "Let his children be fatherless, and his wife a widow.". So if Judas had a wife and children, any son would be a Widow's Son.