I’m guessing she’s either upside down on her mortgage or only has that much in equity in the domicile that will be her anticipated profit from the sale after taxe etc
If you want to work in Thailand you need to have a Work Permit not a DTV or other tourist visa (English teaching only averages around ฿45k a month unless you get a HISO international school or HISO university then the price per month goes up significantly)
DTV is the only Visa as of right now that allows you to remote work in Thailand all other touristy visas do not allow you to do this
$150k or ฿4.9 million baht for a family of 4 might last you 3 years if you manage it right
International school will cost you on average ฿375k per kid per year (฿1.2 million baht per year for your children)
…or higher…most school require the money upfront with no payment system
If you live outside the HISO high rise area you could find a 2-4 bedroom house for around ฿45k-฿60k a month
Food is on you…live like a Thai it will cost you around ฿25k a month…eat like a foreigner you’re looking at ฿40k-฿60k z month for you and your children
Transportation, entertainment, and international Travel will probably run you ฿100k-฿200k a year
And remember the FOREX rate changes daily so that means your budget will vary either up or down month to month