The correct answer is option 'C' - Hastinapur.

Hastinapur, located in the Meerut district of Uttar Pradesh, is an ancient city associated with the Mahabharata. It is known for its rich historical and archaeological significance. During excavations conducted in Hastinapur, numerous iron materials and furnaces have been discovered, providing evidence of iron production during the Iron Age in Uttar Pradesh.

Here is a detailed explanation of the iron findings in Hastinapur:

1. Archaeological Excavations:
- Hastinapur has been a site of extensive archaeological excavations conducted by the Archaeological Survey of India (ASI) and other research organizations.
- These excavations have revealed the existence of various cultural phases, including the Iron Age.
- The Iron Age in Uttar Pradesh is believed to have occurred between 1200 BCE and 600 BCE, characterized by the widespread use of iron tools and weapons.

2. Iron Materials:
- The excavation findings in Hastinapur have unearthed a significant number of iron materials.
- These include iron tools, weapons, ornaments, and other artifacts made from iron.
- The discovery of iron materials suggests the development of ironworking technology during the Iron Age in Uttar Pradesh.

3. Iron Furnaces:
- Along with iron materials, the excavations in Hastinapur have also revealed the presence of iron furnaces.
- Iron furnaces were used for smelting iron ore and extracting metallic iron.
- The discovery of iron furnaces indicates the existence of iron production centers in Hastinapur during the Iron Age.

4. Significance:
- The findings of iron materials and furnaces in Hastinapur provide valuable insights into the technological advancements and socio-economic conditions of the Iron Age in Uttar Pradesh.
- Ironworking played a crucial role in shaping ancient societies, bringing about changes in agriculture, warfare, and trade.
- The discovery of iron materials and furnaces in Hastinapur highlights the importance of the region as a significant center for iron production during that time.

In conclusion, archaeological excavations in Hastinapur, Uttar Pradesh, have revealed the presence of iron materials and furnaces, indicating the existence of ironworking and iron production during the Iron Age. These findings provide valuable insights into the technological advancements and socio-economic conditions of the region during that period.