Theophylact of Ohrid

How did He say that "five in one house will be divided," yet in the enumeration mentioned "six" persons? We answer: one person is counted twice, namely: the daughter and the daughter-in-law are the same person. In relation to the mother she is called a daughter, and in relation to the mother-in-law she is called a daughter-in-law. Thus, "three" — the father, the mother, and the mother-in-law — will be divided "against two" — the son and the daughter. …

Commentary on Luke ↗

Ambrose of Milan

Therefore, even according to the literal meaning, the religious explanation is not lacking for those who understand it piously; however, there is a deeper meaning which we should consider because He added: There will be five divided into one group in the house, three into two, and two into three. For who are the five, when it appears that there is subjection of six persons, of father and son, mother and daughter, mother-in-law and daughter-in-law? …

Exposition of the Gospel of Luke, 7.136-138 ↗

Bede

For from now on, in one house, there will be five divided, three against two, and two against three. They will be divided, father against son, and son against father, mother against daughter, and daughter against mother, mother-in-law against her daughter-in-law, and daughter-in-law against her mother-in-law.

On the Gospel of Luke ↗

Bonaventure

And for this reason He adds: For from this time there shall be five in one house divided, that is, separated from carnal affection; and according to that passage in the penultimate chapter of Deuteronomy: "Who said to his father and to his mother: I know you not, and to his brethren: I know them not, and they knew not their own children. …

Commentary on Luke, Chapter 12 ↗