Question

Read the sentence.

Mrs. Sanchez will help "if you ask her".

The bolded words are what kind of clause?

Answer 1

I believe that is going to be an adverb clause.

adverb clauses function as adverbs and answer such questions as : when, where, why, under what conditions. They modify verbs, adverb, and adjectives. They also have to begin with a subordinating conjunction as well as contain a subject and a predicate.
Mrs. Sanchez -- subject
will help -- verb
if you ask-- adverb clause modifying the verb " will help " answering the question : under what condition.

Answer 2

The clause if you ask her is an adverb clause. 
Since similarly to adverbs, these clauses answers some questions such as where, when, or in this case, under what condition, then this means that they are called adverbial clauses.