This is terribly sad. I am very sorry for your loss.
A photo of her might be too distressing for one or more of the children. If you make something in her favourite colours or from her clothes, put a dab of her perfume on the back so the extra special memory will come through subconsciously and without the risk of upsetting them with a photo. People vary. I have had three close bereavements and I find photos unbearable.