Explanation:

Let’s break down the relation statement:

- "My father's mother" = Sripad's grandmother.

- "Grandmother's only daughter" = Sripad's father's (paternal) sister, aka his aunt, or if his father’s mother only had one daughter, it could be Sripad’s mother if she is that daughter herself.

- "Only daughter's elder daughter" = That aunt or mother’s elder daughter.

- So, the baby girl is the daughter of Sripad’s aunt or mother’s elder daughter— in other words, she is the child of Sripad’s elder sister (if only daughter is mother) or his cousin’s child.

Now, the baby's mother would be the "elder daughter" of his father's mother’s only daughter— which could be his own sister (if mother's her own daughter), or his cousin (if the only daughter is his aunt and not his mother).

Reviewing the options:

- Cousin: This is the person whose daughter is in question.

- Aunt: Would be his father's or mother's sister, not the mother of the baby here.

- Niece: Would be his sibling's daughter.

- Sister-in-law: Not fitting either.

The correct option is Option 1: Cousin

So, the baby's mother is Sripad's cousin.