How should I file tax return for resident alien spouse without SSN or ITIN number ?

You will have to apply for an ITIN.  You can still complete your TurboTax return, but you will have to print and file by mail with the W-7 ITIN application.

In this case what should I enter at spouse's SSN column ?

you mean W7 application right ?

@deenee13 Yes, W-7

See this TurboTax support FAQ for how to file your tax return if your spouse is a nonresident alein - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-credits-deductions/file-taxes-spouse-nonresident-alien/L4AuRKrMd_US_en_US?uid=m7jhv066

If you decide to file your tax return as Married Filing Jointly you must apply for an ITIN with the tax return and you would need to be providing a statement with your tax return that you want your Nonresident Alien Spouse Treated as a Resident.  See IRS Publication 54 Tax Guide for U.S. Citizens and Resident Aliens Abroad starting on page 9 - https://www.irs.gov/pub/irs-pdf/p54.pdf

Go to this IRS website for ITIN information - https://www.irs.gov/individuals/international-taxpayers/general-itin-information

Question while filing W7, what should I enter in field Date of entry into the United States

Should I mention date from the first time spouse enter to USA from I94(This will be from the previous I94) or mention entry date from the most recent I94 entry ?

(As of now she had 2 entries to USA)

The “Date of entry into the United States” must contain the complete date on which you entered the country for the purpose for which you’re requesting an ITIN.  It must match the date on the passport.