Assalaamu alaykum. Please calculate the inheritance according to the following information:
- Does the deceased have male relatives who are entitled to inherit: (A son) Number 1, (A full brother) Number 1, (A half-brother [from his mother]) Number 1, (A nephew from a full brother) Number 1, (A full paternal uncle) Number 1, (A father's half-brother [from the father's father]) Number 1, (A cousin from a full paternal uncle) Number 1, (A husband)
- Does the deceased have female relatives who are entitled to inherit: (A daughter) Number 1, (A grandmother from the mother) Number 1, (A mother of the father's father) Number 1, (A full sister) Number 1
- The deceased's step-mother and his son's wife are pregnant.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If the deceased left behind no other heirs than those mentioned in the question, then her husband gets one fourth of the estate as a fixed share because the deceased had children. Allah, The Exalted, says (what means): {But if they have a child, for you is one fourth of what they leave, after any bequest they (may have) made or debt.} [Quran 4:12]

The grandmother on the mother's side gets one sixth of the estate as a fixed share; Buraydah narrated that the Prophet, sallallaahu ‘alayhi wa sallam, assigned a sixth to a grandmother if the mother (of the deceased) is not among the heirs. [Abu Daawood and An-Nasaa'i - Ibn Khuzaymah and Ibn Al-Aljaarood classified it as saheeh (sound) and Ibn Adiyy said it is strong]

Ibn Al-Munthir said, “Muslim scholars unanimously agreed that the deceased's grandmother gets one sixth of the estate if the deceased's mother is not alive.”

The remainder of the estate is divided among the son and the daughter by Ta’seeb (by virtue of having a paternal relation with the deceased and not having an allotted share, so they get what is left after the allotted shares have been distributed); the male twice the share of the female, as Allah says (what means): {Allah instructs you concerning your children (i.e. their portions of inheritance): for the male, what is equal to the share of two females.} [Quran 4:11]

The great-grandmother on the father's side (the mother of the father's father) gets no share. She is excluded by the presence of the grandmother on the mother’s side because the close maternal grandmother obstructs the distant paternal grandmother from the inheritance according to the view of the majority of the scholars, as stated in Ar-Rahabiyyah (Poem on Islamic Laws of Inheritance). The Fiqh Encyclopedia reads, “Scholars unanimously agreed that the grandmother on the mother's side who is closer in lineage to the deceased obstructs the distant (great) grandmother on the father's side.”

The remaining heirs mentioned in the question get no shares either, including the two pregnant ones, because they are excluded by the presence of the deceased's son.

Hence, the estate should be divided into 36 shares: the husband gets one fourth (9 shares), the grandmother gets one sixth (6 shares), the son gets 14 shares, and the daughter gets 7 shares.

Allah knows best.