Calculate Mary's total pay for the week if she works 41 hours and is paid K6 per hour for the first 36 hours and K8 per hour for any additional hours.

Mary works 36 hours at K6 per hour.

$$\text{Regular pay} = 36 \text{ hours} \times \text{K}6/\text{hour} = \text{K}216$$

Mary works a total of 41 hours. The regular working week is 36 hours.

$$\text{Overtime hours} = 41 \text{ hours} - 36 \text{ hours} = 5 \text{ hours}$$

Mary is paid K8 for each extra hour.

$$\text{Overtime pay} = 5 \text{ hours} \times \text{K}8/\text{hour} = \text{K}40$$

Total pay is the sum of regular pay and overtime pay.

$$\text{Total pay} = \text{Regular pay} + \text{Overtime pay} = \text{K}216 + \text{K}40 = \text{K}256$$

The total pay is K256. This corresponds to option D.

The final answer is $\text{D. K256}$.