Basil is used in many cultures for funarary rites, sprinkled on the graves and planted around the them. Where basil is, no evil can live...is a belief. It is also purifying, an herb of love, and brings prosperity, so with that in mind, basil is a wonderful herb to bless our loved one's passing.
If you desire more than one herb, I would also add rosemary and thyme.
Rosemary can be used in any consecration or blessing and has extremely positive energy that some may even say is "holy". Is is also healing, therefore it can be used to heal the spirit as it adjusts from its physical state into a purely spiritual one.
Thyme is also very healing, and offers energy of love and courage. It is often used to remove all sorrows and ills of the past.
My condolensces for your loss. My blessings to you, your cousin and your family.
P.S.-- Becareful with salt. Although it is purifying and used to bless, it can also harm plants and grass if you use it outdoor. So I tend to stay away from using it when performing any magick outside.