While it’s possible that musical rights are an issue, it’s seems more likely that because those two episodes are the last featuring the Brady’s dog Tiger, they have been removed (perhaps temporarily) from the rotation of the series.
The dog who portrayed Tiger in the series was struck and killed by an automobile during a break in filming and the decision was made to replace him with another dog, who proved to be unable to interact with the series stars. Since the early episodes were often shown out of order, both in syndication as well as when they aired on the network, Tiger’s absence wasn’t that big of a deal. However when the episodes are shown in order, it’s clear that the series intended the dog to be a significant element of the narrative and its death prevents that from occurring.
The name of the missing episodes are:
A Clubhouse Is Not a Home
Additionally, the latter episode (A Clubhouse Is Not a Home) contains some rather misogynistic sentiments which were acceptable in 1969, but would not be appreciated by a modern audience, 50 years later.
Again, it’s more likely that the episodes showing the Brady’s missing dog are the reason that they have been removed from the Hulu package. It can be noted, however, that doghouse remains on the backyard set for much of the first and second season.