I hope you can feel sorry for your loss.
I think, as long as you have that miss in your heart, your old woman will definitely think of you and bless you and your family. Setting up a grave is just a formality, because natural disasters have been washed away and human resources can't stop it.
I think it's ok to find a cemetery and put some things or relics that can represent the old woman. It's just a place to express sadness. You don't have to think so much. It is best to have that heart in your heart.
I hope your family and friends can be happy.