If a couple have been separated for 13 years is the surviving spouse liable for the funeral?

A friends husband died this week, she had been separted from him for 13 years is she liable for the funeral costs. He has 5 childeren but is estranged from most. His sister was down as the next of kin at the care home he was at, he did have money but since he's been in the care home it seems to have all disappeared (his sister had control of his accounts). Is she liable for his funeral under uk law?