El doctor es el señor Guzmán. Él ayuda a mi madre.
Explanation:
This means: The doctor is Mr. Guzmán. He helps my mother. Ayuda is the third person singular of the present tense of the verb "ayudar". It's the most suitable option for the sentence given. "Ayudo" is the first person singular, "ayudas" is the second person singular and "ayudamos" is the first person plural. Since Mr. Guzmán is one person, the only conjugation possible is in the third person of the singular.
