Something really weird happen...

Try exiting your game and wee if it was just a glitch. If that doesn't work find a cheat to move them as "objects" to get them out of bed or just "delete" the bed.

Can you delete 'sleep' from the actions in the top left corner? (click on the picture of the bed)

If not I think all you can do is exit and hope it doesn't happen again :/

I think if you type in 'boolprop testingcheatsenabled true' without the 's and hold shift and click on the bed, you can press force error. A window will pop up. Click reset. Both of the grandparents should pop out of bed right away and the bed will still be there. Hope I helped!