Hi Latoya!
The indirect object pronoun is the word (or phrase) (usually referring to a person) that receives the action of the verb indirectly.
The indirect object pronoun for the 3rd person plural is les . In this case we are talking about "ellas" which is "mis madres" which is 3rd person plural.
If you are talking in the Preterite or simple past "A mis madres les regalé __________". (les is the indirect object pronoun and regalé would be the past tense for 'regalar") just add the gift.
If you are talking in the future : "A mis madres les regalaré ________. " (les is the indirect object pronooun and regalaré would be the future tense for 'regalar") just add the gift.