What if I can not afford to make the pilgrimage to mamas hajj? Is there another way to complete the fifth pillar of Islam or no?
First, if someone is financially incapable of performing hajj, it's not considered an obligation:
In it are clear signs [such as] the standing place of Abraham. And whoever enters it shall be safe. And [due] to Allah from the people is a pilgrimage to the House - for whoever is able to find thereto a way. But whoever disbelieves - then indeed, Allah is free from need of the worlds. -- Qur'an 3:97
This is confirmed by fatwa such as
This includes being able both physically and financially. -- Islam Q&A
As for if there's an alternative, it depends what you mean by "alternative" (The question What are the alternatives of Hajj? was closed as being unclear).
To my knowledge, there's no substitute for hajj in the sense that nothing else ticks the "fifth pillar of Islam" box as complete. Hajj would become obligatory if at a later stage in life it became financially possible.
There's some ahadith which describe acts of worship with the same reward as hajj, e.g
So when the month of Ramadan come, perform Umra, for'Umra in this (month) is equal to Hajj (in reward). -- Sahih Muslim 1255 b (sunnah.com)
Also Sahih al-Bukhari 843 (sunnah.com).
Others are mentioned by IslamWeb. (There's more at What to do When You Can’t Make Hajj, but I'm uncertain about their legitimacy, e.g. the first one is classed as da'if (weak) here: Jami` at-Tirmidhi 586 (sunnah.com).)
As mentioned by others, there is no requirement for Hajj unless the capacity for it exists. If the capacity for that is not available, then there is no fifth pillar for you so there is nothing to make up for it or replace it. Two important additional points though:
❶ - However, there are always other worship you can do, suitable to your circumstances. The reward for an accepted Hajj is Paradise, but you will find similar reward for other acts of worship if you are not able to complete the Hajj.
❷ - If you are sincere in your love for the Hajj to the point where you also feel disheartened that you cannot complete it, you should know that in Islam, the intention is rewarded.
Al-Bukhaari (6491) and Muslim (131) narrated from Ibn ‘Abbaas (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said, relating from his Lord, may He be glorified and exalted: “Allah decreed good deeds and bad deeds, then He explained that. Whoever thinks of doing a good deed then does not do it, Allah will write it down as one complete good deed. If he thinks of doing a good deed and then does it, Allah [may He be glorified and exalted] will write it down between ten and seven hundred fold, or many more. If he thinks of doing a bad deed then he does not do it, Allah will write it down as one complete good deed, and if he thinks of it then does it, Allah will write it down as one bad deed.”
Do not be surprised if on Judgment Day you find a great reward for the sincere intention for Hajj. This is the great mercy of Allah, Who said:
ما يريد الله ليجعل عليكم من حرج ولكن يريد ليطهركم وليتم نعمته عليكم لعلكم تشكرون - ...Allâh does not want to place you in difficulty, but He wants to purify you, and to complete His Favour on you that you may be thankful. (5:6)