Is the husband considered to have fallen short in his duty to his father, and is there a sin he must expiate, due to not visiting his father on holidays, despite visiting him daily after work and speaking with him on the phone, especially after accusations from his mother and sister that his deceased father is displeased with him?

Filial piety towards parents is among the most obligatory duties. What was mentioned about the husband does not indicate his shortcomings; rather, he was keen on being dutiful. Assuming there was a shortcoming, Allah forgives lapses if the person is righteous and repentant. Filial piety can be compensated for after death through supplication, charity, maintaining kinship ties, and honoring their friends. Let the husband be dutiful to his mother, for she is the most deserving of his good companionship.