I saw the last third of this monster movie on Sci-Fi around 1998, and it's been nagging me ever since:

It looked like this bad 80s movie. where i picked up, there was this blob monster (brown and foam-rubbery, had a bunch of tentacles, one with an eye on it, another had a claw), that was living in this house with 3 kids. at one point in the movie, the monster was watching tv, and this alien wearing a helmet came on the screen, possibly the monster's owner. the monster freaked out, and started rampaging throughout the house. at one point, one of the kids went to the parents' room and lifted up the covers. underneath was this gnarled mess, and he said, "it ate them." then the alien from the tv came into their house, and one of the older kids attacked him, breaking his helmet, and causing his head to explode.

i have a bunch more details if you need them to figure it out. please help

crowman

Sounds like Terrorvision.

There are screenshots on that page.