Thank you for including several pages. It was very helpful to see the “B” in question being used in several situations. This does not have a simple all or nothing answer. Each situation needs to be looked at carefully. The real question here is: What are we dealing with? Is the “B” a single letter, an abbreviation, an initial? The answer is actually – all of the above.
Unfortunately EBAE does not offer clear answers for this. The 2009 Literary Lesson Manual is a bit easier to reference. We’ll need to use a combination of the two references. There is no cut and dry answer for this.
According to section 12.2 in the Lesson Manual I suppose you could argue that the “B” always follows Ida and is always used as part of her name so, the letter indicator would not be required because “B” wouldn’t be confused with anything else, context makes it clear.
Lesson Manual 12.2: It should be kept in mind that the purpose of the letter indicator is to avoid confusion of letters or letter combinations with numbers, contractions, or short-form words. If the context is perfectly clear and no such confusion is possible, do not use a letter indicator.
Then again using the following references, there is only instance in your examples where the “B” is followed by period that is not also at the end of sentence. That is the only time a letter sign would not be needed. All the other places would require a letter indicator.
Rule II.12a(2): The letter sign is required when a letter which means a letter stands alone and is not followed by a period indicating an abbreviation.
RULE II.12.a.(4) The letter sign is required when a single letter which means a letter is followed by an apostrophe "s"
Literary Lesson Manual 2009
Pages 12-8 and 12-9: Use the letter indicator / Do not use the Letter Indicator.
13.2 Abbreviations in General: Do not use a letter indicator with a single-letter abbreviation that is followed by a period. Do not use a letter indicator with an abbreviation unless it could be confused with
a word or a short-form word.
13.3 Personal Initials: Place a letter indicator before an initial that is not followed by a period so that it will
not be read as a whole-word contraction.
12.2 Distinguishing Names and Other Words from Short-Form Words: A letter indicator is also used for letter
groupings, such as vocal expressions, plurals of letters…
So ... both of your proofreaders are actually correct. In a case like this you might need to take into account the skill level of the reader. Make a decision which way to go and stay with it throughout the book.
We also need to keep in mind that the rules and guidelines cannot cover everything we encounter in print. - Sometimes we just have to use what we have to make good decisions.
And sometimes we can only agree to disagree.