The given "correct" answer of "Grandfather how did you wake?" is just a literal translation and should not be accepted as a correct answer. The correct answer should be "Good morning?"
It helps to appreciate that different languages have different ways of saying morning greetings
Mwamuka ere ? = Ndau, literally "Have you woken up ?" Günaydın ! = Turkish, literally "Bright day/sun" Bonjour ! = French, literally, "Good day" Livuke njani ? = Ndebele, literally, "You have woken up how ?" Mauka bwanji ? = Nyanja, literally, "You have woken up how ?"
I hope that helps.
I have to disagree. It is not a compound word. It is a morning greeting but it is still asking how they are doing and wether they slept well. It expects an appropriate response. It is important to understand that most of the Swahili greetings are questions about how a person (or something else relevant) is doing. It is not wishing them a good morning or anything else. It is not speaking English with Swahili words. Precision early on leads to easier contextual understanding of a language later.
Look at manyofa's comment below - explains it nicely. For the grammar: ngwarai posted above "It is easier to understand once you get the breakdown of all the pieces that make the word. You can refer to the breakdown of the word "umeamkaje" that I gave on another discussion here https://www.duolingo.com/comment/21048253"