Things to include:
Her kindness (pleasant personality)
How great the care is she gives your dad (her abilites and knowledge).
Dependability as a worker (always on time to work)
Trustworthy

"Dear Sir/Madam:
I am writing this letter of recommendation for (insert name) who is applying for (position) at your (company name).

(Insert the above things to include)

Sincerely,

(your name)