how to hydrate dry hair

[#1]

My aunt has extremely dry hair that has gotten even more dry this summer. She uses hydrating shampoo and conditioner that claim to bring moisture into the hair...but that hasn't happened ever! Her scalp is dry also. She washes her hair every 3 days. She wants a serum or treatment or spray or anything like that to put in her hair from root to ends that will bring moisture and life to her hair. She wants her hair to not feel dry/course/rough. Anyone with the same problem? I need product recommendations/advice.

[#2]

I've had pretty dry hair myself but it was due to heat processing and then later, health issues! I've been able to really repair it with a few different products, but keep in mind that these are just quick solutions and all work differently on everyone.

Sulfate free shampoos that don't contain alcohol and other drying ingredients are great additions. Carol's Daughter, Living Proof and Algenist have a great selection. I love the Alterna UV+ Bamboo Repair Mask which not only smells SO good but its hydrating and softening to my hair.

I also like the Couture Colour Pequi Oil which smells like tropical fruit and is lightweight enough to leave the hair soft and shiny but not greasy, as well as the Alterna Bamboo Smooth Kendi Oil Treatment Oil and the Josie Maran Argan Hair Serum.