Formal:
* പോയി പറയൂ (poyi parayu) - This is the most literal translation and is appropriate for a formal setting.
* പോയി അറിയിക്കൂ (poyi ariyikku) - This means "go and inform" and is also a formal option.
Informal:
* പോയി പറഞ്ഞേക്കൂ (poyi paranjekku) - This is a more casual way of saying "go and tell".
* പോയി പറയൂ, പൊന്നമ്മേ (poyi parayu, ponnmamme) - This is a more affectionate way of saying "go and tell" and uses the term "ponnmamme" (golden mother) to address your grandmother.
Other options:
* ചെന്ന് പറയൂ (chenn parayu) - This means "go and tell" and is a more general phrase.
* ചെന്ന് അറിയിക്കൂ (chenn ariyikku) - This means "go and inform" and is also a general phrase.
Ultimately, the best way to say "go and tell" to your grandmother in Malayalam will depend on your relationship with her and the situation.