Here are the correct answers for each sentence:

1. I don’t know when she **comes/will come** but when she’ll come I’ll give her your book.
**Answer: E) comes/will come**

2. You **will stay** here until your mother **is** ready to leave.
**Answer: A) will stay/is**

3. Many changes **have taken** place since I **was** in my native town 10 ago.
**Answer: D) has taken/am** (Correction: Correct option should actually be "took" instead of "has taken.")

So, the final answers are:
1. **E**
2. **A**
3. **C** (Note: The correct combination is "took/was" not “has taken/am.”)