Oh Grow Up!
Barbara Hanawalt points out the difficulties in interpreting sources: these were records from manorial courts. Perhaps there were plenty of cases where the arrangements were done within family by agreement, requiring no court record.
Perhaps these records represent only the poorer sort, with richer peasants able to establish children in independent households. Or, these were peasants who'd already settled their children but had kept their own place, but were now facing their final years—a second retirement, as it were.
Aging parish priests often hired a caretaker (usually a woman). They might have had a "housekeeper" even when younger, and this wife of convenience stayed with him. Monasteries made special provisions for their elderly, and indeed monasteries served as a kind of retirement home for the lay elderly.
In cities, one of the duties of most guilds was to provide "visitation", which meant coming to visit the sick but also the elderly. Guilds also had regulations and raised monies to give stipends to the poor and aged (and to widows). We also find similar arrangements with shops in towns as we do with farms in the countryside.
The homeless poor simply died of exposure. They show up in coroner reports: frozen, drunk, drowned, or simply dead by a roadside.
The elderly did suffer from mistreatment, from children or from caretakers. They might be robbed or even turned out from their homes. They might suffer varying degrees of neglect.
Coroners' reports show that the elderly died in patterns peculiar to old age: falls were common, especially into water (a well or stream). Dying from heat or cold is another: being more frail, they died where younger men and women did not.
Death by fire was another: a candle by the bed, or an accident around the hearth. Senility was another problem.
There's little cheerful about the end of life.
We can, however, see in the surviving wills a real concern for family and friends, as well as a real concern about the fate of one's soul.
You might be surprised, though, that a significant percentage of peasants made no provision for prayers for their soul. It's difficult to guess at what this might mean, but when a third of all wills have no such provisions, it is probably more than mere poverty.