Morning Sash. I’d prefer at this difficult time.

I much prefer AT ... but IN would work ok (in that everybody would understand). You could say, in HIS time of need.

"At" is the preposition we normally use to specify a time: example: "I'll meet you at 3:00". So, to emphasize WHEN to support him, use "at". However, if your goal is to emphasize the duration of time during which you want to support him, use "in", "through", or "during": "We ought to support him IN/THROUGH/DURING this difficult moment!"

In this situation, the correct preposition is "at." The sentence should be: "We ought to support him at this difficult moment!" Alternatively, you could use the phrase "in the time of need," and the sentence would be: "We ought to support him in the time of need." Both options are grammatically correct, but they convey the message slightly differently. The choice between them depends on your preference and the nuance you want to express.