Kids like routines. How about setting up a daily schedule with times for eating, sleeping, playing inside, outside and cleaning up? I post similar schedules outside my kids' doors when they were this age using pictures to symbolize each activity so they could "read" it themselves. I didn't use actual times, but they understood that at the end of one activity the next would begin.
My second tip would be to stand your ground. No outside until such and such is cleaned up. Then she'll probably scream, which is difficult to handle. Totally ignore it. You may want to reassure her calmly. You're sorry but this is the rule. I keep busy during melt-downs cleaning or reading. She may not make it outside that day, but the next day, when it's time to clean up before going outside, she'll get the picture-Grandma means business.
Lastly, make sure the clean-up is something she can handle. She may not be able to sweep up the crumbs and an entire room full of toys could be overwhelming. You may want to "help" if it's a large mess as long as she's cleaning too.
Best of luck. I'm sure you're doing a lot better than you acknowledged. She's lucky to have you!
Lynn Clarks' book SOS: Help for Parents, seems to be the recommended choice for "help" books. It would be worth your time to pick it up - and it will help you for a lot of years to come.