No apostrophe is generally used today [1998. -p.a.s] with plural nouns that are more descriptive than possessive. Examples they give are steelworkers union, managers meeting and singles bar. I think patients guide fits in that group nicely: After all, the patients indeed do not actually own it.

Beside above, what is the plural of family? Pluralizing family gives us families. Referring to the houses of several families, we say families houses. Forming the plural possessive in such a case is rather simple.

Subsequently, one may also ask, is patience singular or plural?

The noun patience can be countable or uncountable. In more general, commonly used, contexts, the plural form will also be patience. However, in more specific contexts, the plural form can also be patiences e.g. in reference to various types of patiences or a collection of patiences.

What is the plural of tablespoonful?

The plural form of tablespoonful is tablespoonfuls or tablespoonsful.