Just focus your thoughts on how much happiness mother had caused throughout her life. She cared for our comfort and now it’s time for us to think for her well being. So the best idea is to pray to her inner soul (Shudhatma). Pray that she gets the blessings of Lord Simandhar Swami and attains salvation – the ultimate peace. It will be selfish on our part just to think of our happiness. True love is to think about mother’s happiness. That will be a real tribute. At the same time, do pratikraman for all the past deeds and free her from binding any successive karmas.
We know there is no death as such. Just as we change cloths doesn’t mean that the earlier person have ceased to exist. She has left body only, but the Pure Soul is still there, though in another form. So every time you remember mother, pray to her inner soul to attain freedom from bondage of relationship. From your side also you must withdraw your attachment and wish that she receives the blessings of the Lord and gets free from the cycle of life and death.