Translation:The Hungarian families sleep in this hotel.
You could play around with the emphasis, rearrange the word order, or add a couple of more words to the sentence.
If you use emphasis only, you stress "alszanak".
If you rearrange the sentence, you can do something like this:
"Alszanak a magyar családok ebben a szállodában."
And you can add a single word, that expresses the present, the "right at this moment" sense:
"A magyar családok ebben a szállodában éppen alszanak."
Or you can add a present participle, "living", which would also make it clear. It also requires a little rearranging of the sentence:
"Az ebben a szállodában lakó magyar családok (éppen) alszanak." - The Hungarian families living in this hotel are sleeping.
Or another way, with a sub clause:
"A magyar családok, akik ebben a szállodában laknak, alszanak." - The Hungarian families, who live in this hotel, are sleeping.
In Hungarian I have seen that people sometimes use The families or the cats or the guests etc when they mean families or cats or guests in general. There was a sentance earlier on about monkeys and pigs being intelligent animals for example which used "A majmok és a disznók", so could this sentance also be read as "Hungarian families sleep in this hotel"?