She went to Paris to bring back her errant son.

她到巴黎去把误入歧途的儿子领回来。

An errant husband is one who leaves his wife for other women.

路的丈夫是指离开己的妻子去跟别的女人私通的人。

And then one day, in a fit of spring madness, I set out with pruner and lopper to remove a few errant branches.

后来有一天，在春天引起的疯狂冲动中，我拿着整枝器和修枝剪，除掉一些杂乱无章的树枝。