I think the logic subject of this attributive phrase making it... is mother's affection.
I guess you may not well understand the last part of the sentence making it nearly impossible for any man to love me enough to make up for the hole she left in my heart.
The pronoun it here refers to the infinite verbal phrase to love me enough to make up for the hole she left in my heart. This part is actually saying that no man can fulfill the hold left by my mother with their love, because their love to me cannot be compared with my mom's.
Student or Learner