I'm not entirely sure what this specific phrase means as it's rather unclear. It could potentially be a very strange or made - up story title. Maybe 'caught' implies someone witnessed something, 'tied spreadeagle' is a rather odd and perhaps concerning description but without more context it's hard to define precisely.
Well, 'caught' gives the idea of coming across something suddenly. 'Mom' is obvious. But 'tied spreadeagle' is a bit of a mystery. It could be some sort of creative or even disturbing description in a story. Since there's no more context, it's difficult to say for sure what the whole 'caught mom tied spreadeagle story' is about. It might be a unique plot in a mystery or horror story, or just a really strange and random combination of words.