6. D.

For numbers with 2 in the tens place, changing 2 to 1 reduces the total sum by 10; for numbers with 2 in the units place, changing 2 to 1 reduces the total sum by 1.

Numbers with 2 in the tens place are $20, 21, \cdots, 29$, a total of 10; numbers with 2 in the units place are $2, 12, 22$, a total of 3. Therefore, the total reduction is $10 \times 10 + 3 \times 1 = 103$.
6. Meena lists the numbers 1 to 30, and Emilie copies these numbers and changes all the digit 2s to digit 1s. Both then find the sum of the numbers they have written. How much greater is Meena's sum than Emilie's?
(A) 13
(B) 26
(C) 102
(D) 103
(E) 110