My mom is not on good terms with my dad’s mom. She doesn’t really want me to speak to her. What should I do? Her reasoning is that my grandma treated her bad in the past and my grandma doesn’t speak to her currently even tho my moms brother passed away recently but still. My dad takes his mom side.

Obedience to a parent is binding in what is good. The Prophet ﷺ said that obedience is only in what is good (al-Bukhari), so a parent is not obeyed in an order to cut off a relative. Keeping ties does not have to mean visiting. Imam Ibn Baz mentioned that it is kept with good speech, a letter, a phone call, a gift or charity, and Shaykh Ibn Uthaymin said that keeping ties has no fixed limit, not in how long, not in the manner, and that what people count as keeping ties is keeping ties. Alongside that, keep seeking your mother's pleasure with kind words and a good manner, so that you gather the two rights together rather than turning one duty into a quarrel.