1. eligible dependent: no age limit, generally you cannot be in a married or common-law relationship to claim parents as eligible dependent unless they are infirm.
2. caregiver: for parents over 65, net income under $19,435. It's on individual basis, i.e. if one parent over 65, the other under 65, then claim only one. The claimable amount decreases as the parent's income increases.
Done explaining, hope it helps.