What is the compound formed from the combination of the base and a hydrogen ion

Water

Explanation:

When a base react to and hydrogen ion, we can produce water.

According to these equation

H⁺  +  OH⁻   ⇄   H₂O       Kw: 1×10¹⁴

Remember that OH⁻ is determined by a strong base.

This reaction is called neutralization. You can also produce water with a weak base, because OH⁻ are released. For example, let's mention ammonia which is a weak base, it takes protons from water (H⁺)

NH₃  +  H₂O  ⇄  OH⁻  +  NH₄⁺          Kb

When the ammonium ion (acid), reacts to a base, you produce water.

NH₄⁺   +  NaOH →   NH₃ +  H₂O  +  Na⁺

i'm pretty sure its b i might be wrong though!