To start - look at the bright side; your CGM woke you so you didn’t have to wake up to a paramedic kneeling on your chest while another pinned your arm down to test your BG…
On the snack… I always base a snack for a nighttime low on my current BG, how long 'till wake-up, and what my previous day was like. The 15/15 rule alone is NOT applicable here - you want the immediate 15g fast carbs - but add to that more carbs and protein to “cover” you 'till wake-up time. For me… that’s peanut butter and crackers, or a granola bar, or cheese and crackers (after a 6 oz yoo-hoo drink box - 22g carbs, 19 from fructose). The activity level of the previous day will “add” more to my snack - if you’ve depleted your glycogen stores (glycogen is a more complex form of glucose, stored in the liver and long muscles), you’ll need a bit more to replenish them.
If you’re having frequent nighttime lows - the standard recommendation is to reduce insulin, as already noted - but that takes some testing during the nites over a few days, and more detailed tracking of BG levels, to determine that you’re not over-correcting either way. Consider re-calibrating your basal dose - unless it’s evident that your dinnertime bolus is the culprit.