Suggesting Spikenard (Nardostachys jatamansi) is difficult for me because it is critically endangered. It is no longer a sustainable option to use for aromatherapy and essential oil meditations. It is unfortunate. But, there is no other oil that I find comparable. Some suggest Vetiver (Vetiveria zizanioides) or Valerian (Valeriana officinalis), but it's really not the same. Spikenard is exquisite, and has a profound connection to Jesus. Mary Magdalene anointed Jesus’ feet before the Last Supper with what was most likely olive oil infused with spikenard roots:
Then took Mary a pound of ointment of spikenard, very costly, and anointed the feet of Jesus, and wiped his feet with her hair: and the house was filled with the odour of the ointment. — John 12:3 (KJV)
Spikenard has been used for meditation and prayer - the foundations of faith - for centuries. The sixth name of God, according to Islam and Sufism, is al Mu'min, which translates to One who provides Faith. Faith so strong you feel secure and assured.