DD was about 2, and DS hasn't yet.
But it's NOT because I don't want to!
My mother doesn't live close to us, she took DD for 2 days about a year ago because we had to go to a funeral out west and we couldn't bear the thought of driving 12 hours in two days with a 2yo. It was fine.
If my mum lived near us I'd have no problem.
If your little one is used to your mum's house and used to her bed there I'd go for it. The first time is probably the hardest but don't feel guilty, you guys deserve a break and some couple time