In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
The questioner asks: A relative of mine has children and those children neither sit with their grandmother nor do they visit her except occasionally, and the excuse they give is that she is harsh towards them. Her son is the only one who sits with her, so is this [i.e. behaviour of her grandchildren] permissible?
Answer: It is obligated on them to sit with her and make her happy because she is their grandmother. She is like their mother, so it is obligated on them to treat her with kindness and this is part of maintaining the ties of kinship. It is obligated on her son to nurture his children upon this [i.e. to keep the ties of kinship], deal kindly and softly with their grandmother. Likewise it is obligated on the grandmother to be gentle towards these children and not to be harsh towards them if what the children say is true. Abdullaah Ibn Amr [radiyallaahu-anhu] said that the Messenger [sallal-laahu-alayhi-wasallam] said, “He (or she) is not one of us, who does not respect our elders and is not merciful to our youngsters”. [Reported by Imam Ahmad]
[Source: Fadaa’il Al- A’maal page 19’ by Shaikh Muhammad Bin Abdillaah As-Subayyil (rahimahullaah)]