How much does Hajj cost from your country? $90 per month is about $1,000 annually, or $4,000 every 4 years, or $12,000 every four years, considering that the price of Bitcoin will double in 4 years.
According to Google, a Hajj trip costs an average of $7,000. If we say that your country will cost $9,000, and calculating that she may buy gifts when return, then 4 years of savings is sufficient.