In the future, you can try these problems on your own by finding the nouns. Then, find the verb in the group and decide which noun fits with the verb.
In this case, you have three possible nouns: room, hotel, and dad.
The verbs: is, phoning
Now, you can tell that the subject of the sentence must be "dad" because a hotel and a room cannot phone someone.
So far, you have this: "dad is phoning."
Then you can look at all the left over words to decide which ones go together. (Since "My" is capitalized, you know it's the first word of the sentence.)
You will end up with "My dad is phoning for a hotel room."
See if you can attempt your homework on your own next time before you ask for help, okay?