She always rememberswhat her mother told her to avoid. The underlined part is an example of -

• She always remembers what her mother told her to avoid. The underlined part is an example of a noun clause.

• Noun clause: 
- A noun clause is a group of words that band together and act like a noun. Nouns clauses are used when a single word isn't enough. They're always dependent clauses.

একটি বাক্যের চারটি স্থানে Noun clause  বসতে পারে-
1. subject হিসাবে 
2. transitive verb এর object হিসেবে
3. Linking verb এরপরে complement হিসাবে 
4. Preposition এরপরে

প্রদত্ত বাক্যে "what her mother told her to avoid" clause টি verb এর object হিসাবে বসেছে, তাই এটি Noun clause.