There is no specific category for a grandparent to come to the UK. In most cases, they would need to satisfy the requirements of the adult dependent relative route. To be eligible for an adult dependant visa the applicant must be over the age of 18, based outside of the UK and must require long term care from a parent, grandchild, brother, sister, son or daughter who is living permanently in the UK. In order to be eligible you must prove the following: long-term care is required to perform everyday personal and household tasks due to illness, disability or age; the care required isn’t accessible or affordable in the country of residence; and the person who will be being supported in the UK can financially support the relative for at least 5 years, without access to public funds. If granted an adult dependant visa, the applicant will be able to remain in the UK indefinitely without needing to extend their visa or apply for settlement.