Hi Swati,
As we have very limited information to go on and whether any legal agreements have been put in place but, my understanding is that if the money is to cover general expenses like food, travel to appointments etc, then it's probably not taxable, these are often referred to as gratuitous care payments.
If they are "gifts" then there are different implication, which relate to inheritance tax rather than income tax.
If a contract has been signed, then this may be considered as income but again that will depend on whether the hourly rate is the same as, higher than or below the standard rate of pay for a care worker.
If it is at least 20% less than the standard rate then it may not be deemed as taxable.
Both individuals may wish to put any agreement they have in writing, apply to make payments under a Court of Protection, speak to The Office of Public Guardian, a financial advisor or local council about family home care services, here are a few links
Public Guardian practice note (SD14): OPG’s approach to family care payments (web version),
ESM4016 - Particular occupations: careworkers - payments under Court of Protection Order or from trust fund
ESM4156 - Particular occupations: family employment - other than by spouse.
Thank you.