Question

How do you substitute an indirect object pronoun for the expression(a su esposa) for El Sr. Pérez da flores

Answer 1

su esposa means his wife.
u could replace su esposa with her. so ella.
i hope this helped.

Answer 2

Let's see.

Su esposa = His wife

"His wife" can be replaced with simply "her".

I, personally, would say:

"El Sr. Pérez le da flores (a su esposa)."

The le implies he is giving the flowers to a "you - formal, he, she, or it," however it would be impossible to tell without context.