3 year old crying fits?

My daughter does the same thing and my son did it too when he was in daycare. She probably just has a lot of fun at her grandmas house. As long as she stops crying after 5-10 minutes or so I wouldn't worry. Toddlers have a hard time with change. Try giving her 5 minutes before you have to leave and tell her "we will be leaving in 5 minutes" aftr 5 minutes is up say "ok it has been 5 minutes time to go but we will come back to see grandma tomorrow"