I don't think you're going to get a clear cut answer*. Working in your daughter's home technically makes you a household employee. Grandparent baby sitters are generally exempt from social security and Medicare tax, but your daughter's divorced status means that doesn't apply to you**. The easy thing to do is report it as self employment income and pay both the employee and employer share of social security and Medicare tax as "Self employment tax".
*Here's long thread exploring all the options. https://ttlc.intuit.com/community/investments-and-rental-properties/discussion/do-i-have-to-claim-in...
**Wages not counted. Don't count wages you pay to
any of the following individuals as social security or Medicare wages, even if these wages are $2,600 or more during the year.
1. Your spouse.
2. Your child who is under the age of 21.
3. Your parent. Exception: Count these wages if both
the following conditions apply.
a. Your parent cares for your child (including an
adopted child or stepchild) who is either of the following.
i. Under the age of 18.
ii. Has a physical or mental condition that requires the personal care of an adult for at least
4 continuous weeks in the calendar quarter
services were performed.
b. Your marital status is one of the following.
i. You’re divorced and haven't remarried.
ii. You’re a widow or widower.
iii. You’re living with a spouse whose physical or
mental condition prevents them from caring for
your child for at least 4 continuous weeks in
the calendar quarter services were performed.
4. An employee who is under the age of 18 at any time
during the year. Exception: Count these wages if
providing household services is the employee's principal occupation. If the employee is a student, providing household services isn't considered to be their
principal occupation
Reference: https://www.irs.gov/pub/irs-pdf/p926.pdf (page6)
