The correct answer is option 'C', merchants.

Merchants during the 15th century valued the contribution of women in their families. This can be attributed to several factors, including the rise of trade and commerce during this period and the need for family members to actively participate in business activities.

1. Rise of trade and commerce:
During the 15th century, trade and commerce flourished, especially with the expansion of maritime exploration and the discovery of new trade routes. Merchants played a crucial role in this economic growth, and their families were actively involved in their businesses. As a result, women also became important contributors to the family's economic well-being.

2. Family businesses:
Many merchants during this period were involved in family businesses, where multiple family members worked together to run the trade operations. Women were often engaged in various aspects of these businesses, such as bookkeeping, managing finances, and even participating in trade negotiations. Their contributions were highly valued as they played a significant role in the success and growth of the family enterprises.

3. Economic autonomy:
Merchants, unlike aristocrats or scholars, were more focused on economic prosperity and financial gains. They recognized the importance of women's involvement in business activities as it not only enhanced the family's economic status but also provided women with a certain level of economic autonomy and influence within their households. This recognition of women's contributions and their importance within the family set merchants apart from other social classes during the 15th century.

4. Social mobility:
Merchants often experienced social mobility through their economic success. This upward mobility allowed them to challenge traditional gender roles and expectations. As a result, they were more open to empowering women within their families and giving them a higher status and importance compared to other social classes, such as aristocrats or scholars, who were more bound by traditional gender norms and hierarchies.

In conclusion, during the 15th century, merchants recognized the importance of women within their families due to their active participation in trade and commerce. They valued women's contributions as they played a crucial role in the economic success and growth of family businesses. This recognition of women's importance set merchants apart from other social classes, making them prioritize women's role and status within their families. Therefore, the families that gave more importance to women during the 15th century were those of merchants.