To solve this problem, we can use the concept of average age and find the number of men in the group.

Let's assume there are 'x' men in the group.

First, we can find the sum of the ages of all the men in the group before the replacement. Since the average age is the sum of all ages divided by the number of men, we have:

Sum of ages before replacement = Average age before replacement * Number of men

Next, we need to find the sum of ages after the replacement. We know that when the person aged 26 years is replaced by a new person aged 56 years, the average age of the group increases by 6 years. Therefore, the new average age is the average age before replacement plus 6:

New average age = Average age before replacement + 6

We can now find the sum of ages after the replacement using the new average age:

Sum of ages after replacement = New average age * Number of men

Since the sum of ages after the replacement is greater than the sum of ages before the replacement by the age of the replaced person, we have:

Sum of ages after replacement = Sum of ages before replacement + Age of replaced person

Now we can equate the two equations and solve for 'x', the number of men in the group:

New average age * Number of men = Average age before replacement * Number of men + Age of replaced person

Substituting the values given in the problem, we have:

(Average age before replacement + 6) * x = Average age before replacement * x + 26

Simplifying the equation, we get:

6x = 26

Dividing both sides by 6, we find:

x = 26/6

x ≈ 4.33

Since the number of men in the group cannot be a fraction, we can round up to the nearest whole number. Therefore, there are 5 men in the group.

Hence, the correct answer is option B.