Question

Fill in the blank with the correct form of the verb Haber. No___nadie en el mundo más importante que mi mamá. Ella es lo más importante para mí. Hay, hubo, había, hubieron.

Answer 1

The answer is 'Hay'. 

Answer 2

The correct answer is HAY.
The sentence - No hay nadie en el mundo mas importante que mi mama means There is no one in this world more important than my mom.
Another possible option is HABIA, but that would mean - There was no one... so it is better to use HAY to denote the present rather than the past. The other two options are grammatically incorrect in Spanish.