Help! Have to memororize 7 huge books in 4 weeks!!!?

They are not huge books - the first three are quite small. They are also a very easy read; it's not like she's asking you to read clic literature. 4 weeks is easily enough time. You won't need to memorise them, as I can't imagine your mum is going to be really harsh and ask obscure questions or expect a 100% correct answer from you.