One of the giants was 7’9” tall (2.36 m) while the “shorter” one was a mere 7’4” tall (2.23 m) and according to various sources they were indeed twin brothers. They created quite an impression at the Durbar as they literally stood heads and shoulders above the rest. The brothers were known as the Two Kashmir Giants and were elite riflemen in the service of the Maharaja. https://rarehistoricalphotos.com/kashmir-giants/
I would say a lot of columb B. It makes sense for guards to be big, for intimidation alone. After all, the best case is that the guards don't need to fight at all, but keep people with their mere presence from doing something stupid. Being big and imposing is certainly a desirable trait.
According to this article the guards are 2.23m / 7'4" and 2.36m / 7'9" tall. The taller one on the right is standing a bit closer to the camera, so I'll use the other one to measure the prof. Allowing for a bit of imprecision since it's hard to tell exactly where the guard's heel and head are under his clothing, I get the prof being 80% of the guard's height. This puts him at a pretty ordinary 1.79m / 5'10"
Castration is an interesting theory, but it looks closer to a growth hormone cause. That said, there are around 3000 people alive today that are as tall without any such cause.