Ignoring her grandchildren

I am absolutely disgusted by my mother. Short and sweet version: she's mad at me for some unknown petty reason, so she is choosing to give me the silent treatment, which means she's also ignoring her grandchildren (1 and 2 yrs old). I am so sick of her silent treatments that I'm not enabling her anymore. She lives fucking less than 10 minutes away and has seen them ONCE (for a bday party) in 3.5 weeks. She still helped plan the party, but has been very cold (1 or 2 word responses). She still likes my fb posts but no comments anymore. She used to come see them all the damn time. Seems like she told my dad too not to come see us. I find this incredibly childish and selfish. Is she trying to prove a point that I need her or something?? How would you feel if your mother did this??