Is it forbidden in Islam to end all contact with my grandparents from my mothers side? If it is forbidden, then what are the exceptions to ending all contact, and what is the punishment if it is forbidden in Islam?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The grandparents are among the relatives with whom the Muslim is enjoined to uphold the ties of kinship, and it is prohibited to cut the ties with them. Severing the ties of kinship is a reason for being deprived of the mercy of Allah. There is no specific punishment in the worldly life for this; please refer to fatwa 88129 about the gravity of severing the ties of kinship.

There is no excuse to justify severing the ties of kinship completely. It is true that if the relative causes harm, then one may sever the ties with him in a way that wards off his harm, such as not visiting, for instance, but the ties should be upheld by any other means, like calling and the like. That said, we stress that being patient with the harmful relative yields a great reward. Abu Hurayrah reported that a man said to the Messenger of Allah, sallallaahu ‘alayhi wa sallam, "I have relatives with whom I try to maintain good relationships, but they sever the relation with me; whom I treat kindly, but they treat me badly; with whom I am gentle, but they are rough to me." He, sallallaahu ‘alayhi wa sallam, replied, "If you are as you have said, then it is as if you are feeding them hot ashes, and you will continue to have a supporter against them from Allah as long as you do so." [Al-Bukhaari and Muslim]

For more benefit, please refer to fatwa 308854.

Allah knows best.