Meaning of “todita la razón para él”.

Hola Shirley

Here, toda is used with the suffix -ita, but it means the same as toda. 

Here's a lesson about the diminutive. In this specific case, when the speaker is saying "todita" it's really being a bit sarcastic, not so much talking with affection or making something smaller as stated in the lesson. It's got a different nuance.

Saludos

Inma