In terms of what might be useful for you, as one who accepts the Buddha's teaching is...Sn 3.8: Salla Suttahttp://www.accesstoinsight.org/tipitaka ... .irel.html
... however, your mother may not share this world-view and as such, may not find consolation in it. In fact, it might anger her.
Whatever you do, best to regard her with compassion and endeavour to help her through her grief, using the Buddha's teachings to support yourself
(and thus making you of more use to her as a support).
What is the final conviction that comes when radical attention is razor-edge sharp? That the object of the mind is mind-made (manomaya). (Ven. Ñāṇananda)
Having understood name-and-form, which is a product of prolificity,
And which is the root of all malady within and without,
He is released from bondage to the root of all maladies,
That Such-like-one is truly known as 'the one who has understood'. (Snp 3.6)