To create a firewise home, the owners should focus on reducing fire risks and using non-combustible materials. From the options provided, the best changes would be:
B. Increase the space between the tree line and the house
C. Replace wooden exterior with non-combustible siding
These choices help to create defensible space and use materials that are less likely to ignite from embers or flames. The other options either add combustible materials or do not help in fire mitigation.