1. It's about father's love to children.
2. It's about Father's love to children.
3. It's about Fathers' love to children.
4. It's about a father's love to children.
5. It's about the father's love to children.
(Which ones are grammatical?)
2 answers
4 and 5 are best -- but "for" is a better preposition than "to."
number 4 looks like it's the right one