Is telco important to you? You can MNP to XOX for 28 months validity with just minimum RM 10 reload during initial MNP.

Er... No issue on TAC. Maybe just first few days for the system to refresh your no. My sister just did hers in end of Feb, no issue in getting TAC from Maybank, SCB, PBB, HLB. It will no go bankrupt la. You can Google this company, already few years old. Riding on Celcom's network and has 4G now.
My dad's no. was MNP-ed to this telco from Hotlink since 2015 and still surviving.

For more information, please visit XOX thread.

If you just want to keep the number or may be occasionally to accept calls using the number, you can buy talktime extend for just RM1 before your number is going to be terminated. I'm not very sure how long is the grace period after the line becomes inactive but from what I know, most DiGi Prepaid has a grace period of either 75 days (Best Prepaid) or 90 days (Smart Prepaid and LiVE Prepaid). Assuming it comes with a grace period of 90 days, you will need to spend only RM4 a year to keep your number.

Otherwise, you may want to consider Tron Prepaid (using DiGi network) or Friendi (using Celcom network) if you want to keep the line active at all times. A reload of RM10 will keep your line active for 365 days for Tron Prepaid.