In CIT vs Seth Govindram Sugar Mills [1966 AIR 24], the Supreme Court held that a widow cannot be regarded as the karta of her husband's HUF. However, she can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority.

If there is no major age son in the family than elder sister can be made as a Karta of the family otherwise all children are minor's then mother can be made de facto Karta of the family.

Yes it's allow but if the children's are minor, 

Dear Sir/Ma'am,

According to Mitakshara law, only a coparcener can be a Karta or manager of a HUF. Therefore, since a Hindu widow is a member of the HUF but not a coparcener, she cannot be a Karta in her husband's HUF. It is usually the senior-most coparcener of the HUF, that is the Karta. However, the Supreme court of India had stated in one of its judgements that - A widow can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority.

Thank You.

- As per law, upon the demise of Karta, the eldest male member of the family becomes the Karta of the family.

- Further, even the deceased Karta’s wife is alive, the eldest son or any other eldest male member of the family will take over that position.

- However , if no male member or minor , then wife of deceased Karta is allowed. 

No,

She can only be a care taker as the Supreme Court held that a widow cannot be regarded as the karta of her husband's HUF. However, she can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority.

In CIT vs Seth Govindram Sugar Mills [1966 AIR 24], the Supreme Court held that a widow cannot be regarded as the karta of her husband's HUF. However, she can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority.

It means they cannot become Karta as only coparceners are eligible to be Karta of HUF, but will get husband's share in an estate after his death. However, wife can be the guardian of minors in HUF after husband's death until the eldest child becomes a major.

Your mother, being Widow, can become the Karta of HUF. It's allowed.

In CIT vs Seth Govindram Sugar Mills [1966 AIR 24], the Supreme Court held that a widow cannot be regarded as the karta of her husband's HUF. However, she can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority

Yes she can become if she is a Coparcener

a karta can be any coparcenor

coparcenors are those who descend from a common male ancestor 

that is, the descendants of the common male ancestor upto 3 generations below him

so only any person from out of the sons and daughters can become a karta (daughters are recognised as coparcenors after the amendment made to Hindu Succession Act on 9.9.2005)

a widow is not a coparcenor

hence she cannot become a karta

she is merely a member of the HUF and upon partition of the HUF she would get a share equal to that of the son

In CIT vs Seth Govindram Sugar Mills [1966 AIR 24], the Supreme Court held that a widow cannot be regarded as the karta of her husband's HUF. However, she can manage the HUF assets and can represent the same for tax assessment, if the coparceners are minors until the eldest coparcener attains majority. So, answer is no.